Few-layer transition metal dichalcogenides and perovskites are both promising materials in high-performance optoelectronic devices. Here, we developed a self-driven photodetector by creating a heterojunction between few-layer MoS2 and lead-free perovskite Cs2CuBr4. The detector shows a unique property of very high sensitivity in a broad spectral range of 400 to 800 nm with response speed in a millisecond order. Current-voltage characteristics of the heterojunction device show rectifying behavior, in contrast to the ohmic behavior of the MoS2-based device. The rectifying behavior is attributed to the type II band alignment of the MoS2/Cs2CuBr4 heterojunction. The device shows a broadband (400 to 800 nm) photodetection with very high responsivity reaching up to 2.8 × 104 A/W and detectivity of 1.6 × 1011 Jones at a bias voltage of 3 V. The detector can also operate in self-bias mode with sufficient response. The photocurrent, photoresponsivity, detectivity, and external quantum efficiency of the device are found to be dependent on the illumination power density. The response time of the device is found to be ∼32 and ∼79 ms during the rise and fall of the photocurrent. The work proposes a MoS2/Cs2CuBr4 heterostructure to be a promising candidate for cost-effective, high-performance photodetector.
Keywords: Cs2CuBr4; MoS2; heterojunction; lead-free perovskite; photodetector; photoresponsivity.