Cyano-Coordinated Tin Halide Perovskites for Wearable Health Monitoring and Weak Light Imaging.
basic_science · Level V
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- Record sourced from PubMed, PMID 38433566.
- Also identified by DOI 10.1002/adma.202400090.
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Abstract
Low-toxicity tin halide perovskites with excellent optoelectronic properties are promising candidates for photodetection. However, tin halide perovskite photodetectors have suffered from high dark current owing to uncontrollable Sn<sup>2+</sup> oxidation. Here, 2-cyanoethan-1-aminium iodide (CNI) is introduced in CH(NH<sub>2</sub>)<sub>2</sub>SnI<sub>3</sub> (FASnI<sub>3</sub>) perovskite films to inhibit Sn<sup>2+</sup> oxidation by the strong coordination interaction between the cyano group (C≡N) and Sn<sup>2+</sup>. Consequently, FASnI<sub>3</sub>-CNI films exhibit reduced nonradiative recombination and lower trap density. The self-powered photodetector based on FASnI<sub>3</sub>-CNI exhibits low dark current (1.04 × 10<sup>-9</sup> A cm<sup>-2</sup>), high detectivity (2.2 × 10<sup>13</sup> Jones at 785 nm), fast response speed (2.62 µs), and good stability. Mechanism studies show the increase in the activation energy required for thermal emission and generated carriers, leading to a lower dark current in the FASnI<sub>3</sub>-CNI photodetector. In addition, flexible photodetectors based on FASnI<sub>3</sub>-CNI, exhibiting high detectivity and fast response speed, are employed in wearable electronics to monitor the human heart rate under weak light and zero bias conditions. Finally, the FASnI<sub>3</sub>-CNI perovskite photodetectors are integrated with a 32 × 32 thin-film transistor backplane, capable of ultraweak light (170 nW cm<sup>-2</sup>) real-time imaging with high contrast, and zero power consumption, demonstrating the great potential for image sensor applications.