Lead-free CH3NH3SnBr3-xIx perovskite quantum dots for mesoscopic solar cell applications

Highlights: • MASnBr_3-xI_x PQDs are synthesized by a modified hot-injection method. • The bandgaps of PQDs are tuned to widen absorption range. • The PQDs are applied as light harvesters in mesoscopic solar cells. • The PQDs/N719 co-sensitized solar cell achieves an efficiency of 8.79%. Development of high-performance light harvesters is a persistent goal for mesoscopic solar cells. In the current work, lead-free CH₃NH₃SnBr_3-xI_x (x = 0–3) perovskite quantum dots (QDs) are made by integrating Br⁻ ions into host crystal structure. Through tuning Br/I ratio, these perovskite-structured QDs are highlighted with tunable optical bandgaps. When applied as light harvesters for mesoscopic solar cell applications, the devices yield reasonable power conversion efficiency and rapid start-up behaviors. An efficiency of 8.79% is achieved for CH₃NH₃SnBr_3-xI_x QDs and N719 co-sensitized mesoscopic solar cells.