High-Performance All-Inorganic CsPbCl 3 Perovskite Nanocrystal Photodetectors with Superior Stability.

All-inorganic perovskites nanostructures, such as CsPbCl3 nanocrystals (NCs), are promising in many applications including photovoltaics, light-emitting diodes and photodetectors. Despite impressive performance demonstrated, a critical issue remains due to instability of the perovskites in ambient. Herein, we report a method of passivating crystalline CsPbCl3 NCs surface with 3-mercaptopropionic acid (MPA) and superior ambient stability is achieved. Printing of these colloidal NCs on the channel of graphene field effect transistors (GFETs) on solid SiO2/Si and flexible polyethylene terephthalate substrates was carried out to obtain CsPbCl3 NCs/GFET van der Waals heterojunction photodetectors for flexible and visible-blind ultraviolet detection at wavelength below 400 nm. Besides ambient stability, additional benefits of passivating surface charge trapping by the defects on CsPbCl3 NCs and facilitating high-efficient charge transfer between the CsPbCl3 NCs and graphene were provided by MPA. Extraordinary optoelectronic performance was obtained on the CsPbCl3 NCs/graphene devices including high ultraviolet responsivity exceeding 10^6 A/W, high detectivity of 2×10^13 Jones, fast photoresponse time of 0.3 s, and ambient stability with less than 10% degradation of photoresponse after 2400 h. This result illustrates the critical importance of the perovskite NCs surface passivation not only to the performance but also the stability of the perovskite optoelectronic devices.