Transient Optical Properties of CsPbX₃/Poly(maleic anhydride-alt-1-octadecene) Perovskite Quantum Dots for White Light-Emitting Diodes

Poly(maleic anhydride-alt-1-octadecene) (PMAO)-coated green CsPbBr₃ and red CsPbBr_0.6I_2.4 quantum dots (QDs), as the phosphor materials for white light-emitting diodes (WLEDs), are reported. The anhydride groups of PMAO can be bound to the surface ligands of perovskite QDs and act as a protective layer. The results show that CsPbX₃/PMAO (X = Cl, Br, I) presents good crystallinity and excellent luminescence properties. Time-resolved photoluminescence (TRPL) shows that the PL lifetime of CsPbX₃/PMAO is prolonged, and the transient absorption (TA) results show that intraband hot-exciton relaxation and exciton recombination can be slowed down when the CsPbX₃ QDs are coated with PMAO. However, the PL quantum yields (PLQYs) increase for both the green-emitting QDs and the red-emitting QDs after PMAO coating. WLED devices are fabricated by integrating the green CsPbBr₃/PMAO QDs and red CsPbBr_0.6I_2.4/PMAO QDs on the blue GaN chips. The devices show stable white light emission with Commission Internationale de L'Eclairage (CIE) color coordinates of (0.314, 0.291). The results indicate that CsPbX₃/PMAO QDs can be an ideal downconversion fluorescent material for WLED devices.