Controllable Transient Photocurrent in Photodetectors Based on Perovskite Nanocrystals via Doping and Interfacial Engineering

Metal halide perovskites have shown broad prospect in the field of photodetectors due to their high light absorption and long carrier diffusion length. However, the “overshoot”, namely, the transient photocurrent phenomenon in perovskite photodetectors induced by the ineffective charge transportation, crops up frequently and deteriorates the device performances. Here, we realized the control of the transient photocurrent phenomenon in perovskite nanocrystal (NC)-based photodetectors through doping and interfacial engineering. First, Zn2+ ions were used to improve the quality of perovskite NCs and reduce the defects, which were confirmed by photoluminescence (PL) measurements and the Urbach energy. The photoelectric characteristics (on/off ratio increased by approximately 13 times) and transient photocurrent phenomenon of the devices were greatly improved through doping. In addition, Lewis base triphenylphosphine oxide (TPPO) was further adopted as an interfacial passivation layer to eliminate surface defects and improve photoexcited carrier transport, which were certified by PL decay mapping, transient absorption spectroscopy, and current–voltage (I–V) characteristics. The “overshoot” phenomenon finally became almost negligible after doping and interfacial manipulation, and the photocurrent tended to be a horizontal line. These results provide new insight into the control of the carrier transportation and the construction of high-performance perovskite photodetectors as well as other optoelectronic devices.