High-Performance\nBroadband Self-Driven Photodetector Based on MoS₂/Cs₂CuBr₄ Heterojunction

Abstract

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