Cu2ZnSnS4 Quantum Dots as Hole Transport Material for Enhanced Charge Extraction and Stability in All-Inorganic CsPbBr3 Perovskite Solar Cells

All-inorganic CsPbBr3 perovskite solar cells (PSCs) have recently generated tremendous interest in next-generation cost-effective and stable photovoltaic devices. However, the commonly used costly and unstable organic hole transporting material (HTM) has so far prevented the further development and large-scale application of PSCs. In this work, Cu2ZnSnS4 quantum dots (CZTS QDs) are exploited as a novel inorganic HTM for CsPbBr3 PSCs. Due to the well-matched energy levels with the inorganic perovskite layer, a decent power conversion efficiency of 4.84% is achieved, which is quite comparable to the efficiency of the traditional device based on spiro-OMeTAD HTM (5.36%). Moreover, the photoluminescence (PL) and impedance spectroscopy further demonstrate the more effective hole extraction and transfer properties of the CZTS QDs interface layer, making it a promising material for fabricating efficient and stable PSCs toward practical applications.