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

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).