TailoringMultiphoton Absorption and Electron–PhononCoupling of CsPbBr3 Nanocrystals through Rb-Alloying Strategy

Abstract Designing semiconductor nanocrystals (NCs) with strong multiphoton absorption (MPA) and weak electron–phonon (EP) coupling is critical for high-performance near-infrared photodetectors. Yet, such studies remain scarce, restricting the development of related applications. In this work, we have synthesized a series of Cs1–xRbxPbBr3 NCs with tunable emission wavelengths. MPA spectroscopic measurements show that the two-, three-, and four-photon absorption cross sections of the NCs can be enhanced with increasing Rb content, arising from increased exciton binding energy. Temperature-dependent photoluminescence spectroscopy reveals that Rb incorporation can weaken EP coupling and suppress nonradiative recombination. This work provides a feasible alloy strategy for the design of high-performance near-infrared photodetectors.