Single‐Component White‐Light Emitters with Excellent Color Rendering Indexes and High Photoluminescence Quantum Efficiencies

Abstract Broadband white‐light emissions from low‐dimensional organic metal halides have received great attention for applications in energy‐efficient lighting and displays. However, the simultaneous realization of excellent color rendering indexes (CRIs) and high photoluminescence quantum efficiencies (PLQEs) in single‐component white‐light emitters remains a great challenge. Here, a unique 0D organic copper iodide (TPA)CuI₂ (TPA = tetrapropylammonium) is developed, in which the edge‐sharing double trigonal planar [Cu₂I₄]²⁻ dimers are surrounded by the organic cations TPA⁺, forming core/shell structures at the molecular level. These organic copper iodide single crystals exhibit a dual‐band white‐light emission covering the entire visible spectrum with a high PLQE of 84.4% and an excellent CRI of 91.3. In addition, (TPA)CuI₂ nanocrystals are successfully synthesized and exhibit optical properties similar to those of the single‐crystal counterparts. Detailed photophysical studies reveal that the dual‐band emission originates from two self‐trapped emitting states in [Cu₂I₄]²⁻ dimers, whose populations are strongly dependent on the temperature. The promising applications of (TPA)CuI₂ as efficient and high CRI phosphors are demonstrated by a white‐light light‐emitting diode with a Commission Internationale de l'Eclairage coordinate of (0.31, 0.33).