Ion Migration as a New Paradigm to Boost Self-Driven Perovskite Narrowband Photodetectors

摘要

Halide perovskite narrowband photodetectors based on a charge collectionnarrowing mechanism have emerged as a new class of optoelectronic devicesfor monochromatic imaging. However, improving the figures-of-merit of suchnarrowband photodetectors remains challenging due to the inability tomanipulate the major material players in the elusive photoresponse process.Here, a novel approach of manipulating ion migration to enhance thenarrowband photoresponse of self-driven p-i-n type photodetectors is taken byintentionally adding mobile ions into the formamidine and methylaminemixed cation perovskite layer. The excess mobile ions reduce the activationenergy of ion migration, and this facilitated migration orchestrates the ions inthe perovskite layer to re-engineer the energy band, and thus modulates thecharge separation and collection energetics and kinetics, leading to anunprecedented boost of the narrowband photoresponse. The photodetectorbased on this approach achieved a peak responsivity of as high as 112.41 mAW~(?1) at 820 nm at zero bias with a full-width at half maximum of only 22 nmand an over 3-fold improvement in the spectral rejection ratio, making ithighly promising for the next-generation color imaging devices.