Numerical simulation and optimization of a silicon clathrate-based solar cell n-Si136/p-Si2 using SCAPS-1D program

Abstract The aim of this work is to optimize a prototype solar cell based on a real model with type-II silicon clathrate Si136 active layer. For that purpose, a simulation of a ITO/Ag/n-Si136/p-Si/Al solar cell was carried out using the SCAPS-1D software. We have systematically investigated the effects of the thickness of n-Si136 layer and the series resistance RS on the main photovoltaic parameters including: open-circuit voltage (Voc), short-circuit current density (Jsc), conversion efficiency (η), and quantum efficiency QE%. Initial simulation of the structure built from the fabricated model revealed primary weak PV properties with Jsc = 9.621 nA/cm2, Voc = 0.225 V, efficiency of η~10−5% and a maximum output power in the range of PM ~ nW with undetected values for FF. After increasing the thickness of the Si136 clathrate layer, (thickness of Si136 = 100 μm and neglected series resistance RS~0), the optimized device architecture revealed better photovoltaic parameters under AM1.5G spectrum and T = 300 K as: Jsc = 22.65 mA/cm2, Voc = 0.92 V, FF = 67.74% and η = 4.03%, maximum output power of PM = 14.11 mW and quantum efficiency of QE = 48% at 980 nm wavelength. Despite the low conversion efficiency of this prototype solar cell, by this work we aim to shed some light on the possible integration of clathrate phases into photovoltaic devices.