A new p-Ni1−xO : Li/n-Si heterojunction solar cell fabricated by RF magnetron sputtering

Abstract

This study reports the fabrication of p-type Ni1−xO : Li/n-Si heterojunction solar cells (HJSCs) by depositing Li-doped Ni1−xO (p-Ni1−xO : Li) on a n-Si substrate (P+/n) using RF magnetron sputtering. Films deposited on glass substrates at various working pressures were first analysed to estimate the optoelectrical properties of p-Ni1−xO : Li thin films. These experimental results show that the best working pressure was 6 mTorr, which produced a surface roughness of 2.85 nm, a grain size of 19.8 nm, a resistivity of 2.7 Ω cm, a visible transmittance of 49.16%, a work function of 5.32 eV, and a refractive index of 2.54. Although the p-Ni1−xO : Li thin film has a relatively high work function, its conversion efficiency is 2.338% (Voc: 345 mV, Jsc: 22.048 mA cm−2, and FF: 0.307). This study proposes that reduce interface states and improve the optoelectrical properties of p-NiO are two important issues because they can directly and significantly affect the conversion efficiency of p-Ni1−xO : Li/n-Si HJSC. In summary, this high Voc value indicates that p-Ni1−xO : Li thin film is more suitable than ZnO/n-Si structures as an emitter layer for transparent conducting oxide/n-Si HJSC applications.