Modelling and performance analysis of amorphous silicon solar cell using wide band gap nc-Si:H window layer

Poor charge transport mechanism and light-induced degradation effects are among the key factors leading to the degraded performance of single-junction amorphous silicon (a-Si:H) solar cells. Existent photovoltaic configurations, based on amorphous silicon carbide (a-SiC:H) window layer, have established efficiencies in the range of 7–10%. Limited performance of such devices has been addressed by replacing a-SiC:H with a wide band gap (∼2 eV) hydrogenated nano-crystalline silicon (nc-Si:H) layer that reportedly exhibits crystalline properties at small scale. Here, the proposed solar cell based on p-nc-Si:H/i-a-Si:H (buffer)/i-a-Si:H/n-a-Si:H configuration has been simulated with SILVACO TCAD by analysing window and intrinsic absorber layers thickness, as well as doping concentrations. Along with the engineering of p/i interface, in-depth evaluation of absorber defects parameters has also been undertaken in order to reduce the recombination rate. The simulated results of an optimised single-junction device demonstrated an open-circuit voltage (VOC) of 0.865 V, short-circuit current density (JSC) of 21.7 mA/cm2, Fill factor (FF) of 0.69 and power conversion efficiency of 12.93%, which is promising when compared with the solar cell already reported. The proposed structure will provide the platform for further development of low cost and efficient multijunction thin-film amorphous solar cell technology.