Silicon heterojunction solar cell based on organic and transition metal oxide selective carrier contact layer

Abstract

Si heterojunction solar cells based on organic and transition metal oxide selective carrier contact (SCC) layer are developed to bypass the high temperature diffusion process required for the fabrication of p-n junction in conventional Si solar cell. In this work, we design, simulate, fabricate and characterize Si heterojunction solar cells based on organic material, poly(3,4-ethylenedioxythiophene) : polystyrenesulphonate (PEDOT:PSS), and transition metal oxide, molybdenum oxide (MoOx). To have an in-depth understanding of the n-Si/PEDOT:PSS hybrid solar cell, we characterize the heterojunction by reverse recovery transient (RRT) and DC I-V techniques to ascertain its nature. Solar cells are fabricated by spin coating PEDOT:PSS solution on top of n-Si with various doping concentrations (ND) from 10 14-10 17 cm-3. The results of RRT measurement contradicts the Schottky junction model that is commonly assumed for such heterojunction. Instead the n-Si/PEDOT:PSS junction act consistently with the n-p + junction model. The forward bias current injection level is found to influence τp, attributed to the trap saturation effect at n-Si and PEDOT:PSS interface. The interpretation of n-p + junction model is also consistent with DC-IV measurement. Photovoltaic measurement of the n-Si/PEDOT:PSS hybrid solar cell has been conducted to understand the effect of ND on solar cell performance.