Browsing by Author "Shaker, Ahmed"

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Analysis and design of p-n homojunction Sb2Se3 solar cells by numerical simulation
(Elsevier Ltd., 2022-07) Shaker, Ahmed; Salem, Marwa S; Jayan, K. Deepthi
Antimony selenide (Sb2Se3) is considered a promising candidate utilized as an absorber in thin film solar cell (TFSC) technology thanks to its non-toxic and earth-abundant nature besides its reported high absorption co- efficient. To enhance the power conversion efficiency (PCE) of Sb2Se3 solar cells, we report some design sug- gestions by applying device simulation. The numerical model is firstly validated by calibration of simulation results vs those from an experimental Sb2Se3 solar cell structure composed of FTO/CdS/Sb2Se3/Au where CdS serves as an electron transport layer (ETL). Then, the cell is modified to include an embedded p-n homojunction. In contrast to the conventional heterostructure design, a homojunction structure has crucial benefits in terms of both electronic and optoelectronic characteristics such as the extra produced built-in electric field which can increase the transport of photogenerated carriers. Three device configurations are presented and compared. The first and the second cases are when using CdS and ZnOS as ETLs. Utilizing ZnOS ternary compound is found to be more beneficial as its conduction band offset with the absorber layer could be tuned to attain a proper cliff-like band alignment. The third case is when considering homojunction design free from all carrier transport layers. Possible paths for device optimization are investigated to boost the efficiency in a try to overcome the efficiency bottleneck encountered in the Sb2Se3-based quasi homojunction solar cells. All simulations, performed in this study, are done by SCAPS device simulation software under standard AM1.5G one Sun illumination
Analysis of Hybrid Hetero-Homo Junction Lead-Free Perovskite Solar Cells by SCAPS Simulator
(MDPI, 09/12/2021) Salem, Marwa. S; Shaker, Ahmed; Zekry, Abdelhalim; Abouelatta, Mohamed; Alanazi, Adwan; Alshammari, Mohammad T; Gontand, Christian
In this work, we report on the effect of substituting the active intrinsic i-layer on a conventional pin structure of lead-free perovskite solar cell (PSC) by a homo p-n junction, keeping the thickness of the active layer constant. It is expected that when the active i-layer is substituted by a p-n homo junction, one can increase the collection efficiency of the photo-generated electrons and holes due to the built-in electric field of the homo junction. The impact of the technological and physical device parameters on the performance parameters of the solar cell have been worked out. It was found that p-side thickness must be wider than the n-side, while its acceptor concentration should be slightly lower than the donor concentration of the n-side to achieve maximum efficiency. In addition, different absorber types, namely, i-absorber, n-absorber and p-absorber, are compared to the proposed pn-absorber, showing a performance-boosting effect when using the latter. Moreover, the proposed structure is made without a hole transport layer (HTL) to avoid the organic issues of the HTL materials. The back metal work function, bulk trap density and ETL material are optimized for best performance of the HTL-free structure, giving Jsc = 26.48, Voc = 0.948 V, FF = 77.20 and PCE = 19.37% for AM1.5 solar spectra. Such results highlight the prospective of the proposed structure and emphasize the importance of using HTL-free solar cells without deteriorating the efficiency. The solar cell is investigated by using SCAPS simulator.
Automatic Control of a Mobile Manipulator Robot Based on Type-2 Fuzzy Sliding Mode Technique
(MDPI AG, 2022-10) Xu, Xin; Shaker, Ahmed; Salem, Marwa S
In this paper, an automatic control method based on type-2 fuzzy sliding mode control for a mobile arm robot is presented. These types of robots have very complex dynamics due to the uncertainty of the arm parameters and the mobility of their base, so conventional control methods do not provide a suitable solution. The proposed method proves convergence with Lyapunov theory, and its convergence is mathematically guaranteed. A type-2 fuzzy system is responsible for approximating unmodulated dynamics, nonlinear terms, and uncertain parameters. In simulations, the performance of the proposed method with different situations, including uncertainty in arm parameters, uncertainty in mobile robot parameters (arm robot base), uncertainty in load, as well as indeterminacy in modeling have been applied. The comparison with two conventional controllers shows the efficiency and superiority of the proposed method.
Bandwidth Broadening of Piezoelectric Energy Harvesters Using Arrays of a Proposed Piezoelectric Cantilever Structure
(MDPI AG, 8/17/2021) Salem, Marwa S; Ahmed, Shimaa; Shaker, Ahmed; Alshammari, Mohammad T; Al-Dhlan, Kawther A; Alanazi, Adwan; Saeed, Ahmed; Abouelatta, Mohamed
One of the most important challenges in the design of the piezoelectric energy harvester is its narrow bandwidth. Most of the input vibration sources are exposed to frequency variation during their operation. The piezoelectric energy harvester’s narrow bandwidth makes it difficult for the harvester to track the variations of the input vibration source frequency. Thus, the harvester’s output power and overall performance is expected to decline from the designed value. This current study aims to solve the problem of the piezoelectric energy harvester’s narrow bandwidth. The main objective is to achieve bandwidth broadening which is carried out by segmenting the piezoelectric material of the energy harvester into n segments; where n could be more than one. Three arrays with two, four, and six beams are shaped with two piezoelectric segments. The effect of changing the length of the piezoelectric material segment on the resonant frequency, output power, and bandwidth, as well as the frequency response is investigated. The proposed piezoelectric energy harvesters were implemented utilizing a finite element method (FEM) simulation in a MATLAB environment. The results show that increasing the number of array beams increases the output power and bandwidth. For the three-beam arrays, at n equals 2, 6 mW output power and a 9 Hz bandwidth were obtained. Moreover, the bandwidth of such arrays covered around 5% deviation from its resonant frequency. All structures were designed to operate as a steel wheel safety sensor which could be used in train tracks. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.
Comprehensive design and analysis of thin film Sb2S3/CIGS tandem solar cell: TCAD simulation approach
(IOP Publishing Ltd, 2024-06) Salem, Marwa S; Shaker, Ahmed; Aledaily, Arwa N; Alanazi, Adwan; Al-Dhlan, Kawther A; Okil, Mohamed
This research presents a design and analysis of a tandem solar cell, combining thin film wide bandgap Sb2S3 (1.72 eV) and narrow bandgap CIGS (1.15 eV) for the top and bottom sub-cells, respectively. The integration of all thin film layers enhances flexibility, rendering the tandem solar cell suitable for applications such as wearable electronics. To optimize the power conversion efficiency (PCE) of the tandem solar device, advanced technology computer-aided design (TCAD) simulation tools are employed to estimate loss mechanisms and fine-tune parameters for each layer. An experimentally validated optoelectronic model is introduced, calibrated and validated against fabricated reference solar cells for the individual top and bottom cells. The calibrated model is then utilized to propose optimization routines for the Sb2S3/CIGS tandem solar cell. The initial tandem cell exhibits a JSC of 15.72 mA cm−2 and a PCE of 15.36%. The efficiency drop in the tandem configuration is identified primarily in the top cell. A systematic optimization process for the top cell is initiated, exploring various configurations, including HTL-free and ETL-free setups. Moreover, an np homojunction structure for the top cell is proposed. Optimization routines are applied that involve determining optimal thickness and doping concentration of the n-layer, investigating the effect of p-layer doping concentration, and exploring the influence of the work function of the front contact. As a result, the tandem cell efficiency is significantly improved to 23.33% at the current matching point (CMP), with a J SC of 17.15 mA cm−2. The findings contribute to the advancement of thin-film tandem solar cell technology, showcasing its potential for efficient and flexible photovoltaic applications .
Design and analysis of Sb2S3/Si thin film tandem solar cell
(Elsevier, 2023-01) Okil, M.; Shaker, Ahmed; Ahmed, Ibrahim S; Abdolkader, Tarek M; Salem, Marwa S
Antimony sulfide (Sb2S3) and thin crystalline silicon (c-Si) are considered suitable top- and bottom-cell candi- dates for tandem solar cells (TSCs), owing to their natural abundance, non-toxicity, cost-competitiveness, and complementary bandgaps. The current work proposes and investigates a two-terminal (2T) monolithic Sb2S3/Si thin film TSC via TCAD simulation. The Sb2S3 cell, with a bandgap of 1.7 eV, is utilized as a top sub-cell, and the bottom sub-cell is utilized by a thin c-Si cell having a bandgap of 1.12 eV. The calibrated standalone top and bottom cells provide a power conversion efficiency (η) of 4.31% and 14.26%, respectively. Upon incorporating the two cells into a 2T Sb2S3/Si monolithic TSC, the resultant tandem cell achieves an η of 10.10% implying that the top cell should be optimized in order to get a tandem efficiency higher than the bottom cell. Thus, the Sb2S3 cell is optimized by designing the cell without the organic hole transport layer (HTL) (resulting in an np het- erojunction) and engineering the conduction band offset (CBO) between the electron transport layer (ETL) and the Sb2S3 absorber. Then, the tandem structure is optimized starting from the ETL thickness and doping con- centration. Also, the impact of changing the absorber defect density and the series resistance of the top cell on the TSC performance is investigated to demonstrate the maximum available η. At reduced defect density and series resistance, the overall efficiency of the tandem cell is improved to 19.51%. Furthermore, we explored the impact of top and bottom absorber thicknesses on TSC working metrics. At the designed matching point, the tandem efficiency is enhanced to 23.25%, and Jsc also boosts to 17.24 mA/cm2 . The simulation study is intended to provide a tandem configuration that is based on an all-thin-film design which may be suitable for applications like wearable electronics due to its flexibility. All TCAD simulations are performed using the Silvaco Atlas simulator under standard one Sun (AM1.5G, 1000 W/m2 ) illumination.
Design considerations of CdSe solar cells for indoor applications under white LED illumination
(Elsevier B.V, 2024-07) Salem, Marwa S; Shaker, Ahmed; Okil, Mohamed; Li, Luying; Chen, Chao; Aledaily, Arwa N; Al-Dhlan, Kawther A; Zekry, Abdelhalim
This work sheds light on the potential of Cadmium Selenide (CdSe) solar cells for indoor applications. CdSe boasts a wide direct bandgap, high carrier mobility, and a high absorption coefficient, making it an attractive candidate for harnessing ambient indoor light. Our study centers around an experimental solar cell architecture composed of FTO/CdSe/PEDOT:PSS/CuI/ITO, which exhibits a power conversion efficiency (PCE) of 6.00 %. Through a meticulous analysis of the core technological aspects of this cell, we successfully replicate the measured current-voltage characteristics and other experimental data, affirming the validity of our simulation modeling approach. Moving forward, we delve into the design and optimization of CdSe-based solar cells under white LED illumination. We emphasize the pivotal role of a double-hole transport layer (HTL) configuration over a single HTL, with a focus on optimizing the alignment between the HTL/back contact and HTL/absorber interfaces. The strategic incorporation of a heavily doped p-type HTL material, boasting both a deep valence band maximum (VBM) and a shallow conduction band minimum (CBM), is identified as paramount, especially for a deep VBM absorber like CdSe. Adding double HTL materials also facilitates efficient hole collection within the CdSe thin film while mitigating undesirable electron-hole recombination at the critical interface between the hole collection layer and the electrode. The implementation of a double HTL configuration based on CuI/ZnTe:Cu or CuI/BCS significantly enhances performance, resulting in a PCE in the order of 20 % under 200 lux and 2900 K LED illumination. Moreover, we introduce the single HTL design to provide other alternatives for efficiency boosting. Upon increasing the work function of the front contact, it is found that the valence band offset between the HTL and the absorber can be engineered, resulting in a PCE above 21.5 %.
Design of n-i-p and p-i-n Sb2Se3 solar cells: role of band alignment
(IOP Publishing Ltd., 2023-09) Salem, Marwa S; Okil, Mohamed; Shaker, Ahmed; Albaker, Abdullah; Alturki, Mansoor
Investigations into novel device architectures and interfaces that enhance charge transport and collection are necessary to increase the power conversion efficiency (PCE) of antimony selenide (Sb2Se3) solar cells, which have shown great promise as a low-cost and high-efficiency alternative to conventional silicon-based solar cells. The current work uses device simulations to design p-i-n and n-i-p Sb2Se3-based solar cell structures. The n-i-p configuration is investigated by comparing distinct electron transport layer (ETL) materials to get the best performance. While certain ETL materials may yield higher efficiencies, the J–V curve may exhibit S-shaped behavior if there is a misalignment of the bands at the ETL/absorber interface. To address this issue, a proposed double ETL structure is introduced to achieve proper band alignment and conduction band offset for electron transport. A PCE of 20.15% was achieved utilizing (ZnO/ZnSe) as a double ETL and Spiro-OMeTAD as a hole transport layer (HTL). Further, the p-i-n configuration is designed by proposing a double HTL structure to facilitate hole transport and achieve a proper valence band offset. A double HTL consisting of (CuI/CuSCN) is used in conjunction with ETL-free configuration to achieve a PCE of 21.72%. The simulation study is conducted using the SCAPS-1D device simulator and is validated versus a previously fabricated cell based on the configuration FTO/CdS/Sb2Se3/Spiro-OMeTAD/Au.
Enhancement of device characteristics of CNT-TFET: Role of electrostatic doping and work function engineering
(Ain Shams University, 07/06/2022) Ossaimee, Mahmoud; Salah, Ahmed; Gamal, Salah H; Shaker, Ahmed; Salem, M.S
In this work, an Electrostatic Doped Carbon Nanotube Tunneling FET (ED CNT-TFET) has been designed and simulated using a work function engineering technique. An intrinsic CNT is introduced as a channel material and a doped pocket is created between the source and the channel by utilizing an appropriate work function to boost the ON-state current of the device. Moreover, dielectric pocket engineering is applied to boost the high-frequency performance. The simulations, performed in this work, are conducted through a 2D solution of Poisson and Schrodinger equations which are done by utilizing the unbalanced Green function formalism. Simulation results demonstrate that the proposed device structure could improve the ON-current, cut-off frequency, and achieve a low subthreshold swing (SS) value which makes it suitable for low power applications. Additionally, the presented structure could also eliminate ambipolar conduction.
From Crystalline to Low-cost Silicon-based Solar Cells: a Review
(Springer, 2021-03) Abdel-Wahab, Mohamed Okil Shawky; Salem, M. S; Abdolkader, Tarek M; Shaker, Ahmed
Renewable energy has become an auspicious alternative to fossil fuel resources due to its sustainability and renewability. In this respect, Photovoltaics (PV) technology is one of the essential technologies. Today, more than 90 % of the global PV market relies on crystalline silicon (c-Si)-based solar cells. This article reviews the dynamic field of Si-based solar cells from high-cost crystalline to low-cost cells and investigates how to preserve high possible efficiencies while decreasing the cost. First, we discuss the various types of c-Si solar cells with different device architectures and report recent developments. Next, thin-film solar cells with their recent advancements are given. Then, Si nanowires solar cells and their recent results are discussed. Finally, we present the most encouraging tendencies in achieving low-cost solar cells utilizing cheap materials like heavily doped silicon wafers.
Full optoelectronic simulation of all antimony chalcogenide thin film tandem solar cell: Design routes from 4-T to 2-T configuration
(Ain Shams University, 2024-06) Salem, Marwa S; Shaker, Ahmed; Chen, Chao; Li, Luying; Abouelatta, Mohamed; Aledaily, Arwa N; Zein, Walid; Okil, Mohamed
Antimony chalcogenide, as a newcomer to light harvesting materials, is regarded as an auspicious contender for incorporation as a photoactive layer in thin film tandem solar cells (TFTSCs). The current study introduces the design of all-antimony chalcogenide TFTSC comprised of an Sb2S3 (1.7 eV) front subcell and an Sb2Se3 (1.2 eV) rear subcell. The challenges to migrating from four-terminal (4-T) to two-terminal (2-T) designs are highlighted and possible solutions are proposed. To commence, a calibration procedure for the two subcells is conducted in alignment with experimental investigations. The benchmarked solar cells yield a power conversion efficiency (PCE) of 8.08 % for the upper subcell and 10.58 % for the lower subcell. Subsequently, upon integration of both subcells within the initial 4-T Sb2S3/Sb2Se3 TFTSC, the resultant PV cell attains a PCE of 12.27 %. Before transitioning it to a more efficient 2T tandem configuration, we explore alternative inorganic HTL materials to the Spiro-OMeTAD HTL to overcome its practical considerations. Cu2O is found to be the best HTL alternative to be included for both subcells. Upon stacking into the tandem structure, the combined cell exhibited an efficiency of 15.68 % and a notable Jsc of 16.23 mA/cm2 . To further enhance the tandem performance, the device structure is optimized by engineering the CBO of two sub-cells and employing a double ETL design for the front sub-cell. At the considered current matching criterion, the tandem device PCE and Jsc are boosted to 27.86 % and 17.60 mA/ cm2 , respectively. Based on this full optoelectronic analysis, developed in the Silvaco TCAD environment, a 2-T all antimony chalcogenide tandem configuration can be realized and optimized, paving the way for future experimental endeavors.
Full Optoelectronic Simulation of Lead-Free Perovskite/Organic Tandem Solar Cells
(MDPI AG, 2023-02) Salem, Marwa S; Shaker, Ahmed; Abouelatta, Mohamed; Saeed, Ahmed
Organic and perovskite semiconductor materials are considered an interesting combination thanks to their similar processing technologies and band gap tunability. Here, we present the design and analysis of perovskite/organic tandem solar cells (TSCs) by using a full optoelectronic simulator (SETFOS). A wide band gap lead-free ASnI2Br perovskite top subcell is utilized in conjunction with a narrow band gap DPPEZnP-TBO:PC61BM heterojunction organic bottom subcell to form the tandem configuration. The top and bottom cells were designed according to previous experimental work keeping the same materials and physical parameters. The calibration of the two cells regarding simulation and experimental data shows very good agreement, implying the validation of the simulation process. Accordingly, the two cells are combined to develop a 2T tandem cell. Further, upon optimizing the thickness of the front and rear subcells, a current matching condition is satisfied for which the proposed perovskite/organic TSC achieves an efficiency of 13.32%, Jsc of 13.74 mA/cm2 , and Voc of 1.486 V. On the other hand, when optimizing the tandem by utilizing full optoelectronic simulation, the tandem shows a higher efficiency of about 14%, although it achieves a decreased Jsc of 12.27 mA/cm2 . The study shows that the efficiency can be further improved when concurrently optimizing the various tandem layers by global optimization routines. Furthermore, the impact of defects is demonstrated to highlight other possible routes to improve efficiency. The current simulation study can provide a physical understanding and potential directions for further efficiency improvement for lead-free perovskite/organic TSC.
Gate-on-Source TFET Analytical Model: Role of Mobile Charges and Depletion Regions
(Institute of Electrical and Electronics Engineers Inc., 25/10/2021) Eliwy, Mahmoud; Elgamal, Muhammad; Salem, Marwa; Fedawy, Mostafa; Shaker, Ahmed
This study presents a 2-D analytical model for the double gate tunnel FET (DG-TFET). The model considers the gate-on-source overlap that may occur intentionally or unintentionally due to fabrication tolerances. The 2-D Poisson's equation is solved in the main four regions of the structure, namely, the source, channel, drain, and the overlapped region inside the source. The mobile charge inside the channel is taken into consideration. In addition, the source and the drain depletion region lengths are precisely calculated by an iterative technique. Such crucial assumptions and calculations result in accurate expectations of the electrostatic potential. The energy band diagram could be extracted according to the obtained electrostatic potential, and, subsequently, the minimum tunneling width is computed. The impact of channel length and the overlap distance is thoroughly investigated. The results of the proposed model and Silvaco TCAD simulations are compared. The comparison satisfies a good agreement that verifies the validity of the presented model. © 2021 IEEE.
Harmonizing power systems with a 13-level modified Packed U-Cells multi-level inverter: Design and implementation
(Elsevier B.V, 2024-04) Fouda, Sherouk; Salem, Marwa S; Saeed, Ahmed; Shaker, Ahmed; Abouelatta, M; Abou El-Ela, M
Traditional multilevel inverter designs often face complexity challenges, prompting the need for a simplified solution. This study introduces and evaluates the performance of a Modified Packed U-Cells (MPUC) inverter in the realm of multilevel inverter technology. The study addresses challenges associated with conventional multilevel inverters and proposes the MPUC inverter as a solution to simplify the design complexity. The MPUC inverter, utilizing three DC sources and eight switches, presents a groundbreaking thirteen-level output waveform. The primary focus lies in assessing the inverter's performance in terms of Total Harmonic Distortion (THD) and output voltage. Utilizing MATLAB/Simulink, the inverter's performance is evaluated with and without Pulse Width Modulation (PWM) strategies. The results reveal a notable reduction in THD, from 26.25% to 9.91% post-filtering when PWM is not employed. Various multi-carrier Level-Shifted PWM strategies, including PDPWM, PODPWM, APODPWM, and COPWM, are explored to enhance output waveform smoothness and efficiency. Unequal Carrier strategies, specifically UEAPDPWM and UEAPODPWM, emerge as superior in THD management at different frequency ranges. The study further incorporates real-time hardware implementation of the proposed 13-level MPUC topology, highlighting the success of the UEAPD-PWM strategy in improving waveform quality. The research aims to establish a multilevel inverter design protocol meeting international standards and emphasizes the pivotal role of PWM techniques in enhancing waveform quality. This comprehensive evaluation contributes to advancing the field of multilevel inverter technology and sets a benchmark for future research in this domain.
Investigation of Base High Doping Impact on the npn Solar Cell Microstructure Performance using Physically Based Analytical Model
(IEEE, 2021-01) Marwa S, Salem; Zekry, Abdelhalim; Shaker, Ahmed
Recently, there is a rapid trend to incorporate low cost solar cells in photovoltaic technology. In this regard, low-cost high-doped Silicon wafers are beneficial; however, the high doping effects encountered in these wafers render their practical use in fabrication. The npn solar cell microstructure has been found to avoid this issue by the proper design of vertical generation and lateral collection of the light generated carriers. We report on the impact of the p+ base doping concentration, up to 2×1019 cm-3, on the npn microstructure performance to find the most appropriate way for high efficiency. To optimize the structure, a series of design steps has been applied using our previously published analytical model. Before inspecting the high doped base effect, firstly, the n+ emitter is optimized. Secondly, the impact of bulk recombination inside the p+ base is introduced showing the range of optimum base width (Wp). Then, we investigate thoroughly the impact of base doping levels for different base widths to get the optimum Wp that satisfies maximum efficiency. The results show that for p+ base doping concentration ranging from 5×1017 cm-3 to 2×1019 cm-3, the npn microstructure efficiency decreases from 15.9% to 9%, respectively. Although the efficiency is degraded considerably for higher doping levels, the structure still achieves a competitive efficiency at higher doping levels, for which its cost is greatly reduced, in comparison with thin film solar cells. Moreover, using higher doping permits lesser wafer area which could be beneficial for large area solar cells design.
Narrowband Near-Infrared Perovskite/Organic Photodetector: TCAD Numerical Simulation
(Multidisciplinary Digital Publishing Institute (MDPI), 2022-07) Salem, Marwa S; Shaker, Ahmed; Al-Bagawia, Amal H; Aleid, Ghada Mohamed; Othman, Mohamed S; Alshammari, Mohammad T; Fedawy, Mostafa
Narrowband photodetectors (PD) established in the near-infrared (NIR) wavelength range are highly required in a variety of applications including high-quality bioimaging. In this simulation study, we propose a filter-less narrowband PD based on the architecture of perovskite/organic het- erojunction. The most decisive part of the photodetector is the hierarchical configuration of a larger bandgap perovskite material with a thicker film followed by a lower bandgap organic material with a narrower layer. The design of the structure is carried out by TCAD numerical simulations. Our structure is based on an experimentally validated wideband organic PD, which is modified by invok- ing an additional perovskite layer having a tunable bandgap. The main detector device comprises of ITO/perovskite (CsyFA1−yPb(IxBr1−x)3 )/organic blend (PBDTTT-c:C60-PCBM)/PEDOT:PSS/Al. The simulation results show that the proposed heterojunction PD achieves satisfactory performance when the thickness of perovskite and organic layers are 2.5 µm and 500 nm, respectively. The designed photodetector achieves a narrow spectral response at 730 nm with a full width at half-maximum (FWHM) of 33 nm in the detector, while having a responsivity of about 0.12 A/W at zero bias. The presented heterojunction perovskite/organic PD can efficiently detect light in the wavelength range of 700 to 900 nm. These simulation results can be employed to drive the development of filter-less narrowband NIR heterojunction PD.
Numerical analysis and design of high performance HTL-free antimony sulfide solar cells by SCAPS-1D
(Elsevier, 07/12/2021) Salem, Marwa S; Shaker, Ahmed; Othman, Mohamed S; Al-Bagawia, Amal H; Fedawy, Mostafa; Aleid, Ghada Mohamed
Among the various absorbers encountered in thin film solar cells (TFSCs), antimony sulfide (Sb2S3) is considered a suitable candidate as it is a non-toxic and earth-abundant besides its high absorption coefficient. However, some critical issues cause its poor photovoltaic performance. These include unoptimized Sb2S3 layer, interface recombination and cell properties like the ineffective carrier collection and transport. To enhance the power conversion efficiency (PCE) of Sb2S3 solar cell, we suggest some design guidelines by employing device simulation. First, a calibration step is performed vs an experimental arrangement consists of FTO/TiO2/Sb2S3/Spiro-OMeTAD/Au to validate the simulation model. Next, as the organic hole transport material (HTM) often has poor long-term operation stability and demands high-cost fabrication processes, an HTL-free cell is proposed and designed by investigating the impact of the main technological and physical parameters. In the first step in the design of the HTL-free cell, we provide an affinity engineering methodology to tune the conduction band offset between the electron transport layer (ETL) and the absorber. Based on this approach, the most appropriate electron transport material (ETM) is chosen that fulfills the maximum efficiency. Then, an optimization routine is performed to select the most appropriate design parameters and the PCE of the optimized case is found to be about 22%. All simulations, carried out in this work, are performed by SCAPS-1D device simulator under AM1.5G illumination and 300 K temperature.
Numerical analysis of hole transport layer-free antimony selenide solar cells: Possible routes for efficiency promotion
(Elsevier, 2022-07) Salem, Marwa S; Shaker, Ahmed; Abouelatta, M; Alanazi, Adwan; Al-Dhlan, Kawther A; Almurayziq, Tariq S
Amongst the numerous absorbers confronted in thin-film solar cell technology, antimony selenide (Sb2Se3) is regarded as an extremely promising contender as it is a non-toxic and earth-abundant besides its high-level absorption coefficient. To boost the power conversion efficiency (PCE) of Sb2Se3 solar cells, we report some design recommendations by utilizing device simulation. The device model is firstly validated by calibration of an experimental cell having a configuration of FTO/CdS/Sb2Se3/Spiro-OMeTAD/Au. Then, the optimization of a hole transport layer (HTL) free structure is carried out by tuning the conduction band offset between the electron transport layer (ETL) and the Sb2Se3 absorber and by inspecting the key absorber parameters to get the maximum available power conversion efficiency. In this context, the ternary compound material ZnMgO is found to match the optimum band alignment. Moreover, the impact of ETL parameters, like thickness, doping, and surface treatment by ammonia etching, has been analyzed to understand its underlying physics and to provide possible ways for device efficiency promotion. All simulations, conducted in this paper, are accomplished by SCAPS device simulation software under standard one Sun (AM1.5G, 100 mW/cm2) illumination at 300 K.
On the Investigation of Interface Defects of Solar Cells: Lead-based vs Lead-free Perovskite
(IEEE Access, 2021) Salem, Marwa. S; Salah, Mostafa M; Mousa, Mohamed; Shaker, Ahmed; Zekry, Abdelhalim; Abouelatta, Mohamed; Alshammari, Mohammad T; Al-Dhlan, Kawther A; Gontrand, Christian
Perovskite solar cells (PSCs) have drawn significant consideration as a competing solar cell technology because of the drastic advance in their power conversion efficiency (PCE) over the last two decades. The interfaces between the electron transport layer (ETL) and the absorber layer and between the absorber layer and the hole transport layer (HTL) have a major impact on the performance of the PSCs. In this paper, we have investigated the defect interfaces between ETL/absorber layer and absorber layer/HTL of calibrated experimental lead-based and lead-free PSCs. The influence of the defect interfaces is studied in order to find the optimum value for the maximum possible PCE. While the PCE has not been enhanced considerably for the lead-based, it is boosted from 1.76% to 5.35% for lead-free PSCs. Also, bulk traps were found to have minor role in comparison with interface traps for the lead-free cell while they have a significant impact for the lead-based cell. The results presented in this work would shed some light on designing interface defects of various types of practical PSC structures and demonstrates the crucial impact of the interface defects on lead-free vs lead-based PSCs. All simulation studies are performed by using SCAPS-1D simulator.
Performance Improvement of npn Solar Cell Microstructure by TCAD Simulation: Role of Emitter Contact and ARC
(Multidisciplinary Digital Publishing Institute (MDPI), 2022-09) Marwa S, Salem; Zekry, Abdelhalim; Shaker, Ahmed; Abouelatta, Mohamed; Almurayziq, Tariq S; Alshammari, Mohammad T; El-Banna, Mohamed M
In the current study, the performance of the npn solar cell (SC) microstructure is improved by inspecting some modifications to provide possible paths for fabrication techniques of the structure. The npn microstructure is simulated by applying a process simulator by starting with a heavily doped p-type substrate which could be based on low-cost Si wafers. After etching deep notches through the substrate and forming the emitter by n-type diffusion, an aluminum layer is deposited to form the emitter electrode with about 0.1 µm thickness; thereby, the notches are partially filled. This nearly-open-notches microstructure, using thin metal instead of filling the notch completely with Al, gives an efficiency of 15.3%, which is higher than the conventional structure by 0.8%. Moreover, as antireflection coating (ARC) techniques play a crucial role in decreasing the front surface reflectivity, we apply different ARC schemes to inspect their influence on the optical performance. The influence of utilizing single layer (ZnO), double (Si3N4/ZnO), and triple (SiO2/Si3N/ZnO) ARC systems is investigated, and the simulation results are compared. The improvement in the structure performance because of the inclusion of ARC is evaluated by the relative change in the efficiency (∆η). In the single, double, and triple ARC, ∆η is found to be 12.5%, 15.4%, and 17%, respectively. All simulations are performed by using a full TCAD process and device simulators under AM1.5 illumination.