Induced Growth of CsPbBr₃ Perovskite Films by Incorporating Metal Chalcogenide Quantum Dots in PbBr₂ Films for Performance Enhancement of Inorganic Perovskite Solar Cells

Cesium lead bromide (CsPbBr3), an inorganic perovskite material with a large band gap energy (Eg = 2.3 eV), is a great candidate to produce stable and semitransparent perovskite solar cell (PSC) platforms owing to its complete and stable perovskite structure in humid environments. We synthesized quantum dots (QDs) composed of five atoms, copper (Cu), zinc (Zn), indium (In), sulfur (S), and selenium (Se; CZISSe QDs), and incorporated them into CsPbBr3 inorganic perovskite films. To enable the dispersion of CsPbBr3-capped CZISSe QDs in a PbBr2 solution, we used the ligand-exchange method to substitute an inorganic CsPbBr3 shell instead of the long organic capping chains. CZISSe QDs functioned as crystal nuclei seeds in the PbBr2 film and promoted the crystallization of CsPbBr3. Furthermore, they were present in the mesoporous TiO2–CsPbBr3 perovskite layer, improving the extraction and transport of electrons from the CsPbBr3 light absorption layer to the TiO2. Consequently, the power conversion efficiency of the QD-containing inorganic PSC was enhanced by 20.6% compared to that of the QD-free PSC.