Spin‐Deposited Ruddlesden–Popper Polycrystalline Perovskites for Large‐Area High‐Sensitivity Filterless Narrowband Photodetectors with Ultrafast Response Speed

Abstract Filterless perovskite narrowband photodetectors (PNPDs) are highly demanded in color and spectral discrimination, which are typically demonstrated by charge collection narrowing (CCN) effect of perovskite single crystals, showing a limited sensing area and slow response speed. Here, fast‐response, high‐sensitivity PNPDs are demonstrated using spin‐deposited polycrystalline 2D (poly‐2D) Ruddlesden–Popper (RP) perovskite films with thickness of ≈3.6 µm. The strong narrowband excitonic light absorption and limited charge diffusion length of poly‐2D RP perovskites enable a favored long‐wavelength response and a significant suppression of short‐wavelength response to further strengthen the CCN effect. In particular, the photodetection properties, as well as the spectral rejection ratio and central response wavelength, can be finely tuned with an alkyl chain length of the spacer cations. The optimized devices achieve a narrow spectral response with a full‐width at half‐maximum of 12.7 nm, a record high peak specific detectivity of 1.09 × 10 12 Jones and ultrafast response speed with rise/fall times of 5.6/11.5 µs, which outperform the published similar PNPDs. Moreover, a spin‐deposited large‐area sensing array with 6 × 6 PNPDs is fabricated with high consistency, for efficient color and shape discrimination demonstrations. This facile and versatile approach sheds light on the practical applications of large‐area high‐performance filterless PNPDs.