MAPbI<sub>3</sub> Perovskite Multiple Quantum Wells\nfor Enhanced Light Emission and Detection

Multiple\nquantum wells (MQWs) based on thermally evaporated hybrid\nperovskite have been demonstrated in type-I and type-II energy band\nconfigurations by combining MAPbI<sub>3</sub> with bathocuproine (BCP)\nand lead phthalocyanine (PbPC), respectively. Their optoelectronic\nproperties and charge dynamics have been studied, together with their\ndevice potentials. Density functional theory calculations highlighted\nthe major role of surface-localized carriers in ultrathin MAPbI<sub>3</sub> and when BCP or PbPC are on top. This restrained charge exchange\ncan reduce the band bending and minimize the disruption of band alignment,\nconfirming the potential of these interlayer materials for MQWs. Furthermore,\ntype-I MQWs show a remarkable increase in photoluminescence intensity\n(up to 50 times) and a faster radiative recombination rate as MAPbI<sub>3</sub> thickness decreases, demonstrating promising light emission\ncapabilities. Type-II MQWs exhibit extended spectral sensitivity\nand efficient charge separation, significantly improving photodetector\nperformance. This work sets a foundational framework for the further\nexploration of perovskite MQWs in light-emitting and photodetection\napplications.