Atomic-Scale Structural Mechanisms Governing Dopant-Induced Stabilization and Photoluminescence Enhancement in CsPbI3 Quantum Dots

Abstract

Revealing the local atomic structure of doped halide perovskite quantum dots (QDs) is crucial for understanding how metal-ion incorporation tune their optoelectronic properties. In particular, dopant–lattice interactions in CsPbI3 are governed by short-range distortions and dynamic lattice fluctuations that cannot be resolved by conventional diffraction methods. Here, we present a sys- tematic investigation of Zn-doped CsPbI3 QDs over a wide Zn:Pb ratio (0–1.5) by combining optical spectroscopy with extended X-ray absorption fine structure (EXAFS) and X-ray total scattering anal- yses. An optimal Pb:Zn ratio of 1:1.25 yields a markedly enhanced photoluminescence quantum yield of up to 97% accompanied by shortened carrier lifetimes, whereas excessive Zn incorporation deteri- orates the optical performance. EXAFS reveals shortened Pb–I bond lengths, increased coordination numbers, andreducedlocaloctahedraldistortionwithZndopingcomparedwithpristineCsPbI3 QDs. Complementary pair distribution function (PDF) analysis demonstrates that PbI6 octahedral tilting and decreased atomic displacement parameters, indicating stabilisation of lattice fluctuations. These structural modifications collectively weaken electron–phonon coupling and suppress non-radiative recombination pathways, thereby accounting for the enhanced emission efficiency. This work estab- lishes a direct correlation between dopant-induced local structural stabilisation and optoelectronic performance in CsPbI3 QDs.