A high-performance self-powered photodetector based on solution-processed nitrogen-doped graphene quantum dots/all-inorganic perovskite heterostructures

In this work, a self-powered and high-performance vertical type photodetector based on solution-processed nitrogen-doped graphene quantum dots and all-inorganic perovskite nanocrystals heterostructure is achieved. The vertical type NGQDs/CsPbBr3 heterojunction photodetector was fabricated using two steps of standard lithography process and drop-casting method. The vertical type NGQDs/CsPbBr3 photodetector (VTPD) exhibited a nonlinear I-V curve with an extremely low dark current of 0.38 nA and 0.29 nA at forward and reverse bias voltage of 3 V, and - 3 V, respectively. Moreover, the vertical type NGQDs/CsPbBr3 photodetector exhibited superior figure of merits (high-performance) with a light current (257.71 nA), an on/off ratio (670), responsivity (R = 3.21 A/W), specific detectivity (D* = 2.9 x 10(12) J), and an external quantum efficiency (EQE = 270%) under illumination of light source with a wavelength of 520 nm and power intensity of 0.8 mW/cm(2) at bias voltage of 3 V. In addition, the vertical type NGQDs/CsPbBr3 photodetector is confirmed to operate without an external bias voltage demonstrating the obvious photovoltaic characteristics of the device at 0 V. The performance of vertical type NGQDs/CsPbBr3 photodetector (VTPD) is not only surpass the performance of planar type NGQDs/CsPbBr3 photodetector (PTPD) fabricated in this work but also the performance of recently reported self-powered PDs based on carbon/perovskite, and perovskite/perovskite heterostructure. These results pave the way for exploiting solution-processed NGQDs/CsPbBr3 heterojunction to fabricate low-cost, self-powered, and high-performance optoelectronics such as solar cells, light emitting diodes, lasers, and photodetectors.