Efficiency improvement of 25.7% using a voltage biasing transparent electrode for MIS transistor-based silicon solar cells

In this paper, we propose and demonstrate a novel technique on improving the conversion efficiency for a metal-insulator-semiconductor (MIS) transistor-based solar cell by using a voltage biasing transparent electrode. The device structure is consisted of a Si-solar cell, a SiO2 oxide layer, an indium tin oxide (ITO) transparent electrode, and two ohmic-contact electrodes for n-Si and p-Si. The used ITO transparent electrode with a high transmittance at the visible wavelengths and a low sheet resistance are obtained by a sputtering system. The performances of the bare Si-solar cell, the cell with ITO/SiO2 layers, and the cell with ITO/SiO2 layers and ITO electrode applying a bias voltage are sequentially characterized under AM1.5 solar illumination. Comparing the performance with the bare solar cell, the efficiency of the solar cell with ITO/SiO2 films was enhanced of 34.3%. In which, the thin ITO/SiO2 films provide a function like an anti-reflection (AR) coating. Furthermore, the efficiency as a function of bias-voltage was also observed when the ITO transparent electrode was biased at different volts. At 5 V biasing, the efficiency increasing of more 25.7% was obtained in our recently results, which compared the cell with zero volt biasing. The operation mechanism of the biasing dependent is also discussed.