Flexible Quasi‐2D Perovskite/IGZO Phototransistors for Ultrasensitive and Broadband Photodetection

Organic–inorganic hybrid perovskites (PVKs) have recently emerged as attractive materials for photodetectors. However, the poor stability and low electrical conductivity still restrict their practical utilization. Owing to the quantum‐well feature of two‐dimensional (2D) Ruddlesden–Popper PVKs (2D PVKs), a promising quasi‐2D PVK/indium gallium zinc oxide (IGZO) heterostructure phototransistor can be designed. By using a simple ligand‐exchange spin‐coating method, quasi‐2D PVK fabricated on flexible substrates exhibits a desirable type‐II energy band alignment, which facilitates effective spatial separation of photoexcited carriers. The device exhibits excellent photoresponsivity values of >105 A W−1 at 457 nm, and broadband photoresponse (457–1064 nm). By operating the device in the depletion regime, the specific detectivity is found to be 5.1 × 1016 Jones, which is the record high value among all PVK‐based photodetectors reported to date. Due to the resistive hopping barrier in the quasi‐2D PVK, the device can also work as an optoelectronic memory for near‐infrared information storage. More importantly, the easy manufacturing process is highly beneficial, enabling large‐scale and uniform quasi‐2D PVK/IGZO hybrid films for detector arrays with outstanding ambient and operation stabilities. All these findings demonstrate the device architecture here provides a rational avenue to the design of next‐generation flexible photodetectors with unprecedented sensitivity.