CdS-carbon black hybrid nanocomposite buffer layer for antimony sulfide solar cells†

Hydrothermal synthesis of antimony sulfide (Sb₂S₃) has emerged as a suitable method to fabricate Sb₂S₃ solar cells. Conventionally, a CdS film is essential to obtain homogeneous and high-quality Sb₂S₃ films, which in turn improves the photovoltaic performance of Sb₂S₃ devices. However, the CdS film also requires a post-treatment process to achieve the desired electronic conductivity. Herein, we report a hybrid nanocomposite buffer layer consisting of CdS and carbon black nanoparticles synthesized on a TiO₂ film by a one-pot chemical bath deposition route. This method enables high electrical conductivity of the buffer layer with low roughness and n-type nature. Thus, devices based on the nanocomposite buffer layer improve the junction quality at the buffer layer/Sb₂S₃ interface, reducing the trap state recombination. As a result, the power conversion efficiency of the Sb₂S₃ solar cell increases from 4.95 to 6.03%. Such improvement demonstrates that using the nanocomposite buffer layer is a facile and efficient approach to reduce the need for a post-treatment process of CdS.