Improved self-powered perovskite CH₃NH₃PbI₃/SnO₂ heterojunction photodetectors achieved by interfacial engineering...

Lead halide perovskite heterojunctions have been considered as important building blocks for fabricating high-performance photodetectors (PDs). However, the interfacial defects induced non-radiative recombination and interfacial energy-level misalignment induced ineffective carrier transport severely limit the performance of photodetection of resulting devices. Herein, interfacial engineering with a spin-coating procedure has been studied to improve the photodetection performance of CH₃NH₃PbI₃/SnO₂ heterojunction PDs, which were fabricated by sputtering a SnO₂ thin film on ITO glass followed by spin-coating a CH₃NH₃PbI₃ thin film. It has shown that spin-coating of a SnO₂ layer on the sputtered SnO₂ thin films suppressed the surface oxygen vacancies of SnO₂ thin films and up-shifted their conduction band, which suppressed the interfacial non-radiative recombination and enhanced the carriers transport at the CH₃NH₃PbI₃/SnO₂ interface, respectively. Accordingly, improved photodetection performance, such as the reduced dark current and increased photocurrent, has been observed in the CH₃NH₃PbI₃/SnO₂ heterojunction PDs, where the responsivity and detectivity of 0.077 A W^-1 and 2.0 × 10¹¹ jones, respectively, at the zero bias have been demonstrated. These results show a simple way to suppress the interfacial non-radiative recombination and enhance the carrier transport at the interface to fabricate improved perovskite heterojunction PDs in the future.