Fig. 2: Interactions between PPD and the BX2 solvates.
From: Synchronized crystallization in tin-lead perovskite solar cells
a Photos of PbI2 (1 M), SnI2 (1 M), and PbI2 + SnI2 (0.5 M + 0.5 M) solutions without and with PPD additive (0.08 M). The solutions were stored (N2; 20‒30 °C) for 12 h after dissolution. Upper row, DMSO solvent; row below, DMF/DMSO (3:1, v/v) solvent. Note the PbI2 needles precipitated in the DMF/DMSO-based PbI2 solution, the concentration of which should be lower than 1 M. b Absorption spectra of the DMSO-based solutions. c Absorption spectra of the DMF/DMSO-based solutions. d 1H NMR spectra of PPD, PbI2 + PPD, SnI2 + PPD, and SnI2 + PbI2 + PPD in DMSO-d6, and magnified spectra at the ranges of 5.5‒6.8 ppm and 7.0‒8.3 ppm. e FTIR spectra of neat DMSO, and DMSO solutions of PPD, PbI2 + PPD, SnI2 + PPD, and SnI2 + PbI2 + PPD. f Fourier-transformed radial distribution function of EXAFS spectra of the control and target perovskite precursors.
