Investigation of anomalous behaviour in J-V and Suns-Voc characteristics of carrier-selective contact silicon solar cells

Abstract

Process and configuration dependent carrier-selective Ag/ITO/MoOx/n-Si/LiFx/Al silicon solar cells having conversion efficiencies from 6.5% to 14.5% are investigated. Some of the cells’ anomalous characteristics in light J-V and Suns-VOC graphs are analysed by photo-induced capacitance-voltage (C-V), impedance spectroscopy (IS), and voltage- plus light-biased (white, blue and infrared) quantum efficiency (QE). Correlated analysis of cells revealed the physical origin of S-shape in light J-V and turnaround in Suns-VOC graphs. After air exposure of the MoOx film, the charge carrier accumulation at the front interface and inefficient transport through the MoOx layer have led to the anomalous features in light J-V and Suns-VOC graphs of the cell. This is reflected as an additional peak and arc in C-V and IS graphs, respectively. In the absence of the LiFx layer, the cell has shown the only turnaround in Suns-VOC graph due to the Schottky barrier. The IS analysis resolved carrier transport issues at the front junction and back contact of the cells with a distinguished response. The light-bias dependent QE analysis has confirmed the presence of carrier collection barrier at the MoOx/c-Si interface, and the Schottky contact at the back with a different response in EQE spectra.