Short-circuit current density and fill factor improvement by optimizing In2O3:H and metal back reflector layers for p-i-n a-SiGe:H thin film solar cells

Abstract

In this work, high efficiency p-i-n structure hydrogenated amorphous silicon germanium (a-SiGe:H) thin film solar cells were prepared via optimizing hydrogenated indium oxide In2O3:H (IOH) and silver/chromium/aluminum (Ag/Cr/Al) back reflector (BR) layers. Layer wise films including Al, Ag/Cr/Al and IOH/Ag/Cr/Al BR materials were fabricated into solar cells for improving short-circuit current density (Jsc) and fill factor (FF) which in turn enhanced output solar cell performance. Low resistivity, low carrier density and high mobility of IOH layers have been investigated with different water partial pressure ( $${\text{P}}_{{{\text{H}}_{ 2} {\text{O}}}}$$ ). Jsc was enhanced by 13.4% with IOH/Ag/Cr/Al BR structure due to their excellent optoelectronic properties compared to the initial solar cells with Al only. The spectral response of external quantum efficiency at long wavelengths of 550–900 nm was enhanced significantly by adding Ag and Cr with Al as composite electrode. A massive gain in Jsc of 1.13 mA/cm2 was further improved by using optimal $${\text{P}}_{{{\text{H}}_{ 2} {\text{O}}}}$$ with IOH compared to the one without this layer. High efficiency of 9.27% for a-SiGe:H solar cell was successfully fabricated with a high Jsc of 18.40 ± 0.03 mA/cm2 and FF of 69.48%.