Homogeneous Integration of Ruddlesden‐Popper and Dion‐Jacobson Perovskites for Improved Large‐Scale and Bifacial Photodetection

Abstract Ruddlesden‐Popper (RP) and Dion‐Jacobson (DJ) phase metal halide perovskites (MHPs) are known for their improved stability and functionality over bulk MHPs. However, they possess significantly different characteristics, which need to be merged to get overall improved properties. This work demonstrates the homogeneous integration of RP and DJ perovskites formed by incorporating butylammonium (BA) and 1,8‐octyldiammonium (ODA) organic spacers, respectively. The structural and optical investigations confirm the formation of the RP+DJ phase. RP+DJ perovskite vertical‐configuration bifacial photodetectors (FTO/PSK/FTO; active area: 100 mm²) with responsivity of ≈11.94 mA W⁻¹ reveal overall superiority over RP (≈2.75 mA W⁻¹) and DJ (≈0.06 mA W⁻¹) perovskite photodetectors owing to their enhanced crystallinity, horizontal and vertical crystallographic orientation, less strained, decent film morphology, improved charge transport and suppressed charge trapping at device interfaces. Additionally, RP+DJ perovskite photodetectors are studied under dual illumination from the top (λ_ex ≈ 470 nm) and bottom (λ_ex ≈ 528 nm) sides simultaneously to probe the photo‐charge carrier dynamics. RP+DJ perovskite photodetectors show a linear response (≈0.98) for incident power up to 5.72 mW cm⁻² and an operation bandwidth of ≈8 Hz, suggesting their potential for high‐performance optoelectronic devices. Moreover, the demonstrated sandwiched device configuration provides additional protection to the perovskite film, enabling encapsulation‐free as well as metal deposition‐free devices.