Modeling of Photovoltaic Characteristics of a TiO₂/Porous-Si/Si-Based Heterojunction Solar Cell

Abstract

This work is focused on the study of photosensitive structures based on porous Si and film TiO2, which are promising for solar energy. For numerical simulation of the transportation and accumulation of charge carriers in the considered heterostructure, the drift-diffusion approximation of the semiclassical approach was proposed. A device scheme of a solar cell model based on TiO2/porous-Si/Si heterostructures is proposed. Production of photoconverters of solar cells based on the TiO2/porous-Si/Si heterostructure can be carried out according to the standard method supplemented by additional technological operations. Ohmic contacts are formed in the upper and lower parts of the structure above the TiO2 and Si layers. The strip system of contacts is a contact grid, with hatching, the surface coefficient should not exceed 5%. The thickness of the applied layer of photoresist should be 1 μm. Using the PC1D program, the light characteristics of the fabricated structure were calculated (open circuit voltage VOC, short circuit current ISC, fill factor FF and efficiency η), and current-voltage characteristics were plotted. The influence of the thickness and doping level Nd and Na of porous Si and TiO2 layers on the productivity of a heterojunction solar cell TiO2/porous-Si/Si was studied in order to obtain a device with a good conversion efficiency. It was found that the energy conversion efficiency of a TiO2/porous-Si/Si solar cell can reach 22.5 %. Based on the optimized simulation conditions, it was found that the maximum solar cell efficiency is achieved at thicknesses of 100 and 200 nm and donor concentration of Nd=1∙1017 cm-3 and acceptor concentration of Na=1∙1018 cm-3 for TiO2 and porous Si buffer layer, accordingly.