Extended Data Fig. 2: Understanding the interaction between TPPO and CsPbBr3.
From: Efficient all-thermally evaporated perovskite light-emitting diodes for active-matrix displays
a, Density functional theory calculation: TPPO binding with the unsaturated lead at the perovskite edge through P = O:Pb. The binding energy is 0.73 eV with a bond length of 2.4 Å. b, Calculated binding energy between CsPbBr3 and different Lewis-base additives (TPPO, TPPS: triphenylphosphine sulfide, and TPMM: triphenylmethyl mercaptan) with lone pair electrons. c, Calculated density of state for CsPbBr3 and CsPbBr3-TPPO. The red region represents the density of the passivated defect state. The calculated density of states (DOS) indicates that TPPO could act as an electron-pair donor to bind with the unsaturated lead dangling bonds, and thus eliminate the trap states that existed in the band edge of CsPbBr3, inhibiting the trap-assisted non-radiative recombination processes. d, Fourier transform infrared (FTIR) spectra of thermally evaporated pure TPPO, PbBr2-TPPO, CsPbBr3-TPPO, and CsPbBr3 films. The infrared peak at 1192 cm−1 of TPPO arises from the P = O stretching vibration, and shifts to 1185 cm−1 in the case of PbBr2-TPPO and CsPbBr3-TPPO, confirming the chemical bonding of P = O:Pb. e, Pb 4 f core-level XPS spectra of CsPbBr3 and CsPbBr3-TPPO films. Once again, the shift of XPS spectrum for TPPO-incorporated film confirms the chemical bonding of P = O:Pb. f, Photoluminescence spectra of the perovskite films with various TPPO contents. For instance, 40% TPPO represents the deposition rates ratio of TPPO/CsPbBr3 40%.
