Chang, Chih YuChih YuChangHuang, Ming HsuanMing HsuanHuangChen, Kuan ChunKuan ChunChenHuang, Wen TseWen TseHuangKamiński, MikołajMikołajKamińskiMajewska, NataliaNataliaMajewskaKlimczuk, TomaszTomaszKlimczukChen, Jia HaoJia HaoChenCherng, Ding HuaDing HuaCherngLu, Kuang MaoKuang MaoLuPang, Wei KongWei KongPangPeterson, Vanessa K.Vanessa K.PetersonMahlik, SebastianSebastianMahlikLeniec, GrzegorzGrzegorzLeniecRU-SHI LIU2024-05-082024-05-082024-04-2308974756https://scholars.lib.ntu.edu.tw/handle/123456789/642402Increasing demand for near-infrared-II (NIR-II) light sources requires improved NIR-II phosphors. We present a series of phosphors codoped with Cr3+ and Ni2+ that possess NIR-II emission with an unprecedented internal quantum efficiency (IQE) of 97.4%. Our study reveals an energy transfer mechanism involving clusters of Cr3+ where luminescent centers are closely matched in energy and where the Ni2+ emission intensity can be tuned through sintering temperature. The profound electron paramagnetic resonance (EPR) studies disclose the interaction between Cr3+ clusters and Cr3+-Ni2+ pairs, further proving the cause of such a high IQE and the significance of Cr3+ clusters. This work provides promising pathways for the development of NIR-II light-emitting diodes with outstanding efficiency by suggesting a new energy transfer source of Cr3+enjournal article10.1021/acs.chemmater.4c004382-s2.0-85190861859https://api.elsevier.com/content/abstract/scopus_id/85190861859