Doping and Defect Engineering of CuO for Enhanced Performance in Si Heterojunction Solar Cells

CuO thin films are attractive candidates for solar cell absorber layers due to their natural abundance and suitable band gap. This study investigates the potential of pristine and doped (Zn, Mg, and Al) CuO thin films in Si-based heterojunction solar cells through both experimental fabrication and SCAPS-1D simulations under AM 1.5 illumination. Simulations revealed that doping significantly enhanced the solar cell efficiency, increasing it from 5% for pure CuO to over 24% in doped samples, approaching theoretical predictions. However, introducing parasitic resistance reduced the efficiency to 3.99% for pure CuO and 5.77% for Al-doped CuO. Additionally, oxygen defects were found to influence device performance, with higher efficiency observed when interstitial oxygen (O_i) defects dominated over oxygen vacancies (V_o). Experimental results confirmed the photovoltaic behavior in all fabricated devices. However, the efficiency of the fabricated device was very low compared with the simulated results for pristine and Zn- and Mg-doped CuO-based devices. Notably, Al-doped CuO exhibited a substantial increase in efficiency from 0.42% in pure CuO to 6.52%. The findings demonstrate that controlled doping and defect engineering in the absorber layer play vital roles in enhancing the performance of Si/CuO heterojunction solar cells. This approach holds promise for developing cost-effective and efficient photovoltaic technologies.