FIG. 4.
Photovoltaic performance of bismuth-based perovskite-inspired materials compared to the performance of [HC(NH2)2]0.73[CH3NH3]0.27Pb(Br0.008,I0.992)3 (FAMA) and CH3NH3PbI3 (MAPbI3) perovskites. (a) Power conversion efficiency, (b) short-circuit current density, and (c) open-circuit voltage of the devices compared to the radiative limits (RL), as well as 75%, 50%, and 25% of the RL. Note that the color coding of the RL lines is the same in (a)–(c), and these are labeled in part (c) only for clarity. The photovoltaic performance data are obtained from Refs. 8 and 66–74. (d) Open-circuit voltage loss against reported Urbach energy compared against the theoretical open-circuit voltage loss for different band gaps (Eg) if non-radiative losses due to the Urbach energy were the only loss process. The thermal energy at room temperature is marked with the dashed black line. The colors of the data points for the materials in (a)–(d) are based on the band gaps of the materials: ∼1.6 eV (brown), 1.6–1.8 eV (red), 1.9 eV (pink), 2.2–2.3 eV (green), and 2.6 eV (blue). Details on the calculations of the radiative limits and losses can be found in Refs. 8, 11, and 12. The data on Urbach energy and open-circuit voltage loss are obtained from Refs. 8, 12, 44, 68, 75, and 76. Note that Cs2AgBiBr6 and BiOI have open-circuit voltage losses below those calculated owing to uncertainties in the Urbach energy of the film used in devices and the dark currents in the devices deviating from those calculated from the ideal blackbody spectrum. Nevertheless, this plot shows that the Urbach energies for both materials are strong contributors to their high open-circuit voltage losses.