Electroluminescent Solar Cells Based on CsPbI₃ Perovskite Quantum Dots

All-inorganic CsPbX₃ (X = Cl, Br, I, or mixed halides) perovskite quantum dots (QDs) exhibit tunable optical bandgaps and narrow emission peaks, which have received worldwide interest in the field of both photovoltaics (PVs) and light-emitting diodes (LEDs). Herein, it is reported a discovery that CsPbI₃ perovskite QD solar cell can simultaneously deliver high PV performance and intense electroluminescence. In specific, the multifunctional CsPbI₃ QD film is fabricated through a simple yet efficient solid-state-ligand exchange process using a tailored organic ligand triphenyl phosphite (TPPI). The function of QD surface manipulation using TPPI here is proven to be twofold, balancing the carrier transport and effectively passivating the QD surface to produce conductive and emissive QD film. The CsPbI₃ perovskite QD solar cell delivers a champion efficiency of 15.21% with improved open circuit voltage and high fill factor. Concurrently functioning as a red LED, the CsPbI₃ perovskite QD solar cell outputs electric power to light conversion efficiency approaching 4%, a record value for QD electroluminescent PVs. The results here indicate that these versatile perovskite QDs may be a promising candidate for fabricating multifunctional optoelectronic devices.