Browsing by Author "Salem, Marwa. S"

Now showing 1 - 3 of 3

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.
Gate Dielectric Constant Engineering for Alleviating Ambipolar Conduction in MOS-GNRFET
(The electrochemical journal, 07/09/2021) Mahmoud, MennaTullah; Salem, Marwa. S; Ossaimee, M
In the current study, a gate dielectric constant engineering approach is reported to minimize the ambipolar conduction in MOSFET-Like Graphene Nano Ribbon (MOS-GNRFET). The dielectric constants, k, over different regions of the device play a crucial role in energy band diagram modification. So, by choosing suitable values of k over the drain, channel and source regions, the band-to-band tunneling (BTB) path at the drain–channel interface can be minimized. Subsequently, the ambipolar current in MOS-GNRFET is decreased substantially. In addition, the high frequency performance is investigated considering the cutoff frequency, fT, as a figure of merit. It has been found that the proposed technique reduces the ambipolar current by about four orders, decreases OFF-current by two orders and consequently increases ON/OFF current ratio by two orders giving a value of 2.9 × 1010. It has been found that the proposed technique does not deteriorate the gate capacitance which, in turn, enhances fT that reaches about 23 THz, making the proposed structure efficient for digital and analog performance.
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.