Optoelectronic response of semiconductor CsPb1_xCdxBr3 nanocrystals: Role of Cd element

Cd element alloyed perovskite nanocrystals is an effective strategy to improve the photovoltaic performance. However, it still remains necessary to further explore the effect of Cd element in photo-physics and opto-eletronic performance. Here, the optoelectronic characteristics of Cd alloyed CsPbBr3 nanocrystals (CsPb1_xCdxBr3 NCs) is investigated systemically. With the incorporation of Cd element, the crystal structure passes through from cubic (x = 0.0) to hexagonal phase (x = 0.85). The linear absorption cross sections at 400 nm monotonically decrease with x increasing, while the two-photon absorption action cross section at 800 nm increases to the maximum of 5.7 x 105 GM at x = 0.10. Meanwhile, the thermal activation model perfectly explains the optoeletronic performance of prototype photodetectors based on CsPb1_xCdxBr3 NCs whose photo-current and photo-responsivity reach the maximum at x = 0.27. Finally, the corresponding primitive flexible photodetector shows negligible change with the device bending. Our results offer a deep insight into the strategy of Cd element alloyed into perovskite nanocrystals and broaden their application in nonlinear optical imaging or photo-detector.