Avoidance of Inverse Isotope Effect and Synergistic Adjustment of Perovskite Hardness Coupled with Improvement of Thermal Stability

doi:10.16553/j.cnki.issn1000-985x.2025.0256

Abstract

Abstract: Perovskite materials show broad prospects in the field of new photovoltaic devices and high-performance photodetectors due to their excellent photoelectric conversion efficiency and adjustable band gap characteristics. However， perovskite has the problem of insufficient long-term stability under actual working conditions， which seriously restricts its large-scale commercial application. To address this critical bottleneck， this study proposed a molecular engineering strategy based on methyl deuteration （—CD₃）， which selectively replaced the hydrogen atoms on the methyl terminus of organic cations （CH₃NH₃⁺） in perovskites with deuterium （D） isotopes. This approach systemically enhances material stability without significantly altering the electronic structure of the material. Compared with the traditional deuteration treatment of the ammonium （—NH₃） site， the methyl deuteration strategy effectively avoids the inverse isotope effect that may arise from quantum tunneling effect of N—D bonds， thereby precluding the risk of potential stability decline. This study reveales that the introduction of deuterium atoms enables the modulation of material hardness and enhances its thermal stability. At the level of carrier dynamics， deuteration effectively suppresses the dynamic disorder of the crystal， thereby significantly enhancing the carrier lifetime of the material.

Key words: perovskite; methyl deuteration; isotope effect; band gap regulation; structural disorder

CLC Number:

O734

LI Zhuoyue, YANG Mengke, ZHOU Siqi, ZHANG Jianfeng, MA Yundong, HU Ziyu, ZHENG Guozong. Avoidance of Inverse Isotope Effect and Synergistic Adjustment of Perovskite Hardness Coupled with Improvement of Thermal Stability[J]. Journal of Synthetic Crystals, 2026, 55(5): 746-752.

Figures/Tables 4

Fig.1 Comparison of some properties of CH3NH3PbCl3 and CD3NH3PbCl3. （a） Single crystal images；（b） XRD patterns；（c） NMR spectra；（d） Raman spectra

Fig.2 Ultraviolet-visible （UV-Vis） absorption spectra and ultraviolet XPS of CH3NH3PbCl3 and CD3NH3PbCl3. （a） UV-Vis absorption spectra；（b） band gaps calculated from Tauc plots；（c） summary of band gaps for samples from different batches；（d） elemental measurement spectra of samples； XPS of Cl? （e） and Pb2+ （f）

Fig.3 Differences in mechanical properties， thermal stability， and electrical conductivity between CH3NH3PbCl3 and CD3NH3PbCl3. （a） Nanoindentation tests （load-depth curves） of single crystals；（b） TG/DTG curves；（c） electrical conductivity

Fig.4 Steady-state PL spectra （a） and time-resolved PL decay curves and lifetime fitting curves （b） of CH3NH3PbCl3 and CD3NH3PbCl3

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