Abstract
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.