Performance Enhancement of Solution-Processed Submicrometer CISSe Solar Cells via Rear Interfacial Passivation and...

The fabrication of high-performance submicrometer copper indium sulfoselenide (CISSe) absorbers from environmentally friendly solutions offers a promising strategy to reduce material consumption and enable large-scale production. However, the presence of a carbon residual layer in solution-processed absorbers typically limits device efficiency. To address this issue, this research employs a copper-indium-thiourea-N,N-dimethylformamide (Cu-In-TU-DMF) solution to fabricate high-quality CISSe (without a carbon residual layer). Furthermore, to mitigate nonradiative recombination loss, randomly distributed dielectric silica (SiO2) nanospheres (250 nm in diameter) are incorporated near the rear interface of the absorber. As a result, the proposed strategy simultaneously improves open-circuit voltage (Voc), short-circuit current density (Jsc), and fill factor (FF), resulting in a champion device efficiency of 9.9%, with a Voc of 496.2 mV, a Jsc of 29.4 mA/cm2, and an FF of 67.6%. Moreover, when the SiO2 nanospheres are applied to passivate the rear interface of a semitransparent CISSe device fabricated on an indium tin oxide (ITO) back contact, all photovoltaic parameters are boosted. In summary, our research demonstrates that embedding SiO2 nanospheres into the absorber layer provides a simple and effective strategy for enhancing the performance of solution-processed solar cells. This method can be easily applied to other solution-based photovoltaic technologies, such as copper indium gallium selenide (Cu(In,Ga)Se2), copper zinc tin selenide (Cu2ZnSnSe4), antimony selenide (Sb2Se3), silver bismuth sulfide (AgBiS2), and perovskite solar cells.