Photoinduced charge separation in Q1D heterojunction materials: Evidence for electron-hole pair separation in mixed-halide $MX$ solids

TL;DR

This study demonstrates charge separation in mixed-halide $MX$ complexes through resonance Raman experiments and theoretical modeling, showing electron-hole pair separation driven by band hybridization, with implications for device applications.

Contribution

It provides experimental evidence and theoretical explanation for charge separation in mixed-halide $MX$ materials, highlighting polaron localization and hybridization effects.

Findings

Electron polarons prefer PtBr segments; holes localize in PtCl segments.

Strong band hybridization drives charge separation.

Experimental and theoretical results agree on polaron localization patterns.

Abstract

Resonance Raman experiments on doped and photoexcited single crystals of mixed-halide $MX$ complexes ($M$=Pt; $X$=Cl,Br) clearly indicate charge separation: electron polarons preferentially locate on PtBr segments while hole polarons are trapped within PtCl segments. This polaron selectivity, potentially very useful for device applications, is demonstrated theoretically using a discrete, 3/4-filled, two-band, tight-binding, extended Peierls-Hubbard model. Strong hybridization of the PtCl and PtBr electronic bands is the driving force for separation.