High-Performance All-Inorganic CsPbCl₃ Perovskite Nanocrystal Photodetectors with Superior Stability

All-inorganic perovskites nanostructures, such as CsPbCl₃ nanocrystals (NCs), are promising in many applications including light-emitting diodes, photovoltaics, and photodetectors. Despite the impressive performance that was demonstrated, a critical issue remains due to the instability of the perovskites in ambient. Herein, we report a method of passivating crystalline CsPbCl₃ NC surfaces with 3-mercaptopropionic acid (MPA), and superior ambient stability is achieved. The printing of these colloidal NCs on the channel of graphene field-effect transistors (GFETs) on solid Si/SiO₂ and flexible polyethylene terephthalate substrates was carried out to obtain CsPbCl₃ NCs/GFET heterojunction photodetectors for flexible and visible-blind ultraviolet detection at wavelength below 400 nm. Besides ambient stability, the additional benefits of passivating surface charge trapping by the defects on CsPbCl₃ NCs and facilitating high-efficiency charge transfer between the CsPbCl₃ NCs and graphene were provided by MPA. Extraordinary optoelectronic performance was obtained on the CsPbCl₃ NCs/graphene devices including a high ultraviolet responsivity exceeding 10⁶ A/W, a high detectivity of 2 × 10¹³ Jones, a fast photoresponse time of 0.3 s, and ambient stability with less than 10% degradation of photoresponse after 2400 h. This result demonstrates the crucial importance of the perovskite NC surface passivation not only to the performance but also to the stability of the perovskite optoelectronic devices.