Dark Current in Broadband Perovskite-Organic Heterojunction Photodetectors Controlled by Interfacial Energy Band Offset.
basic_science · Level V
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- Record sourced from PubMed, PMID 38888509.
- Also identified by DOI 10.1002/adma.202401206.
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Abstract
Lead halide perovskite and organic semiconductors are promising classes of materials for photodetector (PD) applications. State-of-the-art perovskite PDs have performance metrics exceeding silicon PDs in the visible. While organic semiconductors offer bandgap tunability due to their chemical design with detection extended into the near-infrared (NIR), perovskites are limited to the visible band and the first fraction of the NIR spectrum. In this work, perovskite-organic heterojunction (POH) PDs with absorption up to 950 nm are designed by the dual contribution of perovskite and the donor:acceptor bulk-heterojunction (BHJ), without any intermediate layer. The effect of the energetics of the donor materials is systematically studied on the dark current (J<sub>d</sub>) of the device by using the PBDB-T polymer family. Combining the experimental results with drift-diffusion simulations, it is shown that J<sub>d</sub> in POH devices is limited by thermal generation via deep trap states in the BHJ. Thus, the best performance is obtained for the PM7-based POH, which delivers an ultra-low noise current of 2 × 10<sup>-14</sup> A Hz<sup>-1/2</sup> and high specific detectivity of 4.7 × 10<sup>12</sup> Jones in the NIR. Last, the application of the PM7-based POH devices as NIR pulse oximeter with high-accuracy heartbeat monitoring at long-distance of 2 meters is demonstrated.