Fingerprints of Iodoplumbate Chains in the Optical Absorption of Lead-Halide Perovskite Solution Precursors

Solvent-solute interactions in precursor solutions of lead halide perovskites (LHP) critically impact the quality of solution-processed materials, as they lead to the formation of a variety of polyiodide plumbates that act as building blocks for LHP. The formation of [PbI$_{2+n}$]$^{n-}$ complexes is often expected in diluted solutions while coordination occurring at high concentrations is not well understood yet.In a combined \textit{ab initio} and experimental work, we demonstrate that the optical spectra of the quasi-one-dimensional iodoplumbate chains PbI$_2$(DMSO)$_4$, Pb$_2$I$_4$(DMSO)$_6$, and Pb$_3$I$_6$(DMSO)$_8$ formed in dimethyl sulfoxide solutions are compatible with the spectral fingerprints measured at high concentrations of lead iodide. This finding suggests that the optical spectra of LHP precursor solutions at high concentration should be interpreted accounting for the presence of iodoplumbate chains as well.

PDF Abstract