Fig. 12. (a) Absorption characteristics of MAGeI3, CsGeI3 and FAGeI3 in comparison with CsSnI3. (b) Schematic energy level diagram of CsGeI3, FAGeI3 and MAGeI3. (c) J–V curves of photovoltaic devices fabricated with different Ge halide perovskites. Time-resolved UV-vis measurements to investigate the ambient stability of the germanium perovskite samples of (d) MAGeI3 and (e) MAGeI2.7Br0.3 and (f) absorption intensity at 510 nm versus time. (a–c) Ref. 149. (d–f) Ref. 151.
