Unveiling the role of CdO incorporation in enhancing ultraviolet absorption efficiency on CdTe solar cell performance

The development of efficient and stable CdTe solar cells critically depends on the optimization of the window layer, particularly for enhancing ultraviolet (UV) light absorption and minimizing interfacial recombination. In this work, cadmium oxide (CdO) thin films were explored as alternative buffer layers due to their favourable optoelectronic properties, including a wide band gap energy (2.18–2.5 eV) and controllable resistivity in the range of 101-104 Ω·cm. Both CdO and conventional CdS films were synthesized via the Chemical Bath Deposition (CBD) technique on FTO (SnO2:F) substrates, and their structural, morphological, optical, and electrical properties were systematically analysed. CdO was integrated into the window region of CdTe based photovoltaic devices in two heterostructure configurations: CdO/CdS and CdS/CdO. The interplay of individual material properties and interface phenomena significantly influenced device performance. Remarkably, the CdO/CdS configuration yielded a substantial enhancement in key photovoltaic parameters. Compared to the standard CdS only window design, devices incorporating CdO/CdS exhibited a fourfold increase in shunt resistance (from 2003 Ω $$\:\cdot\:$$ cm2 to 9362 Ω $$\:\cdot\:$$ cm2), along with a notable rise in power conversion efficiency from 8 to 14%. These findings highlight the potential of CdO as a strategic component in CdTe solar cell architecture, offering improved UV photon harvesting and superior interfacial quality. The results not only underscore the viability of CBD-grown CdO thin films in scalable solar cell fabrication but also provide new insights into interface engineering for high-efficiency thin film photovoltaics.