Probing intrinsic defects of aluminium-doped CuO thin films for solar cell applications

Intrinsic defects in semiconductor thin films play a significant role in determining their optoelectronic properties. In this work, we investigated the impact of aluminium doping on the intrinsic defects and, thereby, the optoelectronic properties of CuO thin films deposited via spray pyrolysis. Doping considerably influenced the inherent defects of CuO thin films. Al³⁺ doping enhanced oxygen interstitial defects and suppressed oxygen vacancy defects. The presence of oxygen interstitials and an improvement in the crystallinity of the films resulted in favourable changes in the properties of the films. The observed modifications in the properties had a profound significance in improving the performance of CuO-based optoelectronic devices such as solar cells. Further, the ease of formation of oxygen interstitial defects compared to other possible defects and their favourable role in enhancing optoelectronic properties were confirmed through theoretical calculations. Thus, via comprehensive experimental and theoretical investigation, this study provides significant insights into the formation of defects and their influence on the properties of Al-doped CuO films.