Characterizations and reliability studies of LEDs with red phosphor applied to vehicle rear signaling light sources

Phosphor-converted red light-emitting diodes (PC-RED-LEDs), based on a blue InGaN emitter combined with a red phosphor, are investigated as an alternative to native AlInGaP red LEDs for automotive rear signaling lamps. A requirement-driven selection matrix is proposed to rank candidate light sources against regulatory compliance (ECE/SAE), chromaticity, luminance, luminous efficacy, thermal stability, and technology maturity. Two PC-RED-LED candidates from different suppliers are benchmarked against a mature native red LED using the same opto-electro-thermal workflow. Luminance, CIE 1931 chromaticity coordinates, and luminous efficacy are evaluated over a junction-temperature range of 25-120 ◦ C under representative drive conditions. One PC-RED-LED candidate satisfies both ECE and SAE chromaticity constraints, whereas the other is noncompliant. Compared with the native red LED (13 cd/mm 2 and 47 lm/W at T j = 55 ◦ C ), the compliant PC-RED-LED provides competitive luminance (11.8 cd/mm 2 ), reduced thermal sensitivity (0.2%/ ◦ C versus 0.6%/ ◦ C), and an efficacy of 39 lm/W at T j = 55 ◦ C . These results highlight the potential of PC-RED-LEDs to improve the thermal robustness of rear signaling lamps, dedicated long-term reliability testing remains required for automotive qualification. • Phosphor families for automotive red conversion were benchmarked against RoHS and optical/thermal criteria. • pc-RED-LED architecture (blue InGaN pump + red converter) was evaluated for rear-signaling requirements. • Luminous flux and chromaticity stability were characterized versus drive current and junction temperature. • Reliability-relevant stresses were discussed with emphasis on downconverter/package degradation pathways. • Selection guidelines are provided to trade off color purity (FWHM), efficiency, and high-temperature robustness