Transition from Dion-Jacobson hybrid layered double perovskites to 1D perovskites for ultraviolet to visible photodetection.

New perovskite phases having diverse optoelectronic properties are the need of the hour. We present five variations of R 2 AgM(iii)X 8 , where R = NH 3 C 4 H 8 NH 3 (4N4) or NH 3 C 6 H 12 NH 3 (6N6); M(iii) = Bi 3+ or Sb 3+ ; and X = Br - or I - , by tuning the composition of (4N4) 2 AgBiBr 8 , a structurally rich hybrid layered double perovskite (HLDP). (4N4) 2 AgBiBr 8 , (4N4) 2 AgSbBr 8 , and (6N6) 2 AgBiBr 8 crystallize as Dion-Jacobson (DJ) HLDPs, whereas 1D (6N6)SbBr 5 , (4N4)-BiI and (4N4)-SbI have trans -connected chains by corner-shared octahedra. Ag + stays out of the 1D lattice either when SbBr 6 3- distortion is high or if Ag + needs to octahedrally coordinate with I - . Band structure calculations show a direct bandgap for all the bromide phases except (6N6) 2 AgBiBr 8 . (4N4) 2 AgBiBr 8 with lower octahedral tilt shows a maximum UV responsivity of 18.8 ± 0.2 A W -1 and external quantum efficiency (EQE) of 6360 ± 58%, at 2.5 V. When self-powered (0 V), (4N4)-SbI has the best responsivity of 11.7 ± 0.2 mA W -1 under 485 nm visible light, with fast photoresponse ≤100 ms.