Intrinsic Stabilization of CsPbI ₃ Nanowires via Y ³⁺ Doping for Enhanced Optical Performance

One-dimensional (1D) CsPbI3 nanowires (NWs) are promising for nanoscale optoelectronic applications due to their strong quantum confinement and anisotropic charge-transport characteristics, yet their practical use is severely limited by high defect density and poor structural stability. Here, we report an intrinsic stabilization strategy for CsPbI3 NWs via controlled Y3+ doping. CsPbI3 nanocrystals with different Y3+ contents were synthesized by a hot-injection method and subsequently transformed into 1D NWs through a solvent-induced phase conversion process. Structural characterizations demonstrate that Y3+ ions substitutionally occupy Pb2+ sites, inducing slight lattice contraction without generating secondary phases. Importantly, Y3+ incorporation markedly suppresses nonradiative defect states and enhances optical performance. The CsPbI3 NWs with an optimal Y3+ doping level of 20% exhibit the highest photoluminescence (PL) intensity and a 3-fold increase in average exciton lifetime, from ∼35 ns for pristine NWs to ∼110 ns after doping. Temperature-dependent PL analysis reveals an increased exciton binding energy from 413.6 to 491.2 meV and an enhanced longitudinal optical phonon energy from 465.2 to 614.6 meV, indicating strengthened exciton confinement and improved thermal stability. Moreover, the 20% Y3+-doped CsPbI3 NWs retain approximately 90% of their initial PL intensity after 28 days of ambient exposure, whereas pristine NWs undergo rapid degradation. These results demonstrate that Y3+ doping enables effective lattice-level defect regulation and intrinsic stabilization of CsPbI3 NWs, providing a robust and quantitative design strategy for high-performance and long-lifetime perovskite optoelectronic devices.