Photo-thermal crosstalk in AlGaInP and InGaN LEDs under dual-wavelength excitation

Light-emitting diodes (LEDs) in high-density arrays are increasingly limited by opto-thermal crosstalk, which degrades color fidelity, uniformity, and on-line calibration. This study provides a systematic, measurement-driven analysis of intra-chip opto-thermal coupling and material-dependent crosstalk in single-chip AlGaInP (red) and InGaN (green) dies under 405 nm and 470 nm dual-wavelength excitation. Spatially resolved micro-photoluminescence (μ-PL) mapping was combined with calibrated DC electro-thermal characterization to extract per-chip absorption, PL efficiency, effective thermal resistance, and PL temperature sensitivity. Experimental results demonstrate strong material dependence of photo→thermal behavior. PL efficiency decreases with increasing excitation intensity due to thermal quenching in both materials, but dual-wavelength effects diverge: AlGaInP red chips show further suppression of optical-crosstalk efficiency under 405+470 nm excitation (example: 9.67% → 6.11%), consistent with dominant photo→thermal attenuation; by contrast, InGaN green chips exhibit pronounced nonlinear enhancement (example: 18.52% → 68.13%), consistent with QCSE screening, band-filling mitigation, and carrier-localization–driven radiative gain.A physics-informed photo–thermal scalar model was derived to separate direct PL gain from indirect photo→thermal attenuation and to link measurable radiometric quantities to junction heating.