Transition from Dion–Jacobson hybrid layered double perovskites to 1D perovskites for ultraviolet to visible photodetection†
b
and
Sayan
Bhattacharyya
*a
Abstract
New perovskite phases having diverse optoelectronic properties are the need of the hour. We present five variations of R2AgM(III)X8, where R = NH3C4H8NH3 (4N4) or NH3C6H12NH3 (6N6); M(III) = Bi3+ or Sb3+; and X = Br− or I−, by tuning the composition of (4N4)2AgBiBr8, a structurally rich hybrid layered double perovskite (HLDP). (4N4)2AgBiBr8, (4N4)2AgSbBr8, and (6N6)2AgBiBr8 crystallize as Dion–Jacobson (DJ) HLDPs, whereas 1D (6N6)SbBr5, (4N4)–BiI and (4N4)–SbI have trans-connected chains by corner-shared octahedra. Ag+ stays out of the 1D lattice either when SbBr63− 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)2AgBiBr8. (4N4)2AgBiBr8 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.
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