Numerical Insights into the Influence of Electrical Properties of n-CdS Buffer Layer on the Performance of SLG/Mo/p-Absorber/n-CdS/n-ZnO/Ag Configured Thin Film Photovoltaic Devices

Abstract

A CdS thin film buffer layer has been widely used as conventional n-type heterojunction partner both in established and emerging thin film photovoltaic devices. In this study, we perform numerical simulation to elucidate the influence of electrical properties of the CdS buffer layer, essentially in terms of carrier mobility and carrier concentration on the performance of SLG/Mo/p-Absorber/n-CdS/n-ZnO/Ag configured thin film photovoltaic devices, by using the Solar Cell Capacitance Simulator (SCAPS-1D). A wide range of p-type absorber layers with a band gap from 0.9 to 1.7 eV and electron affinity from 3.7 to 4.7 eV have been considered in this simulation study. For an ideal absorber layer (no defect), the carrier mobility and carrier concentration of CdS buffer layer do not significantly alter the maximum attainable efficiency. Generally, it was revealed that for an absorber layer with a conduction band offset (CBO) that is more than 0.3 eV, Jsc is strongly dependent on the carrier mobility and carrier concentration of the CdS buffer layer, whereas Voc is predominantly dependent on the back contact barrier height. However, as the bulk defect density of the absorber layer is increased from 1014 to 1018 cm−3, a CdS buffer layer with higher carrier mobility and carrier concentration is an imperative requirement to a yield device with higher conversion efficiency and a larger band gap-CBO window for realization of a functional device. Most tellingly, simulation outcomes from this study reveal that electrical properties of the CdS buffer layer play a decisive role in determining the progress of emerging p-type photo-absorber layer materials, particularly during the embryonic device development stage.

An in-depth analysis of nucleation and growth mechanism of CdS thin film synthesized by chemical bath deposition (CBD) technique

“…This permitted the optimization of minority carrier transport. Nonetheless, thicker CdS films induced a Schottky barrier effect and enhanced minority carrier transmission 14 . Doping semiconductors after the incorporation of acceptors or donors into the crystal lattice was a conventional strategy for reducing electrical resistivity 15 .…”

New systematic study approach of green synthesis CdS thin film via Salvia dye

“…This allowed optimised minority carrier transport. However, if the CdS films were thick, it induced a Schottky barrier effect and improved the minority carrier transportation 16 . Doping semiconductors after incorporating acceptors or donors into the crystal lattice was a conventional method for reducing electrical resistivity 17 .…”

9.3% Efficient Flexible Cu2ZnSn(S,Se)4 Solar Cells with High‐Quality Interfaces via Ultrathin CdS and Zn0.8Sn0.2O Buffer Layers

“…[21,27] We performed simulation with solar cell capacitance simulator (SCAPS) (Simulation model parameters for SCAPS are shown in Table S2, Supporting Information) to reveal the band alignment of the heterojunction, as shown in Figure 3. [35][36][37][38] The negative CBO of CZTSSe/ZnO with a "cliff-type" state leads to serious recombination at the heterojunction interface, while the slightly positive CBO of CZTSSe/Zn 0.8 Sn 0.2 O (ZTO) with a "spike-type" state reflects the most favorable conduction band arrangement to reduce interface recombination.…”