Molecular engineering towards efficientwhite-light-emitting perovskite

Abstract

Low-dimensional hybrid perovskites have demonstrated excellent performance as white-light emitters. The broadband white emission originates from self-trapped excitons (STEs). Since the mechanism of STEs formation in perovskites is still not clear, preparing new low-dimensional white perovskites relies mostly on screening lots of intercalated organic molecules rather than rational design. Here, we report an atom-substituting strategy to trigger STEs formation in layered perovskites. Halogen-substituted phenyl molecules are applied to synthesize perovskite crystals. The halogen-substituents will withdraw electrons from the branched chain (-R-NH3+) of the phenyl molecule. This will result in positive charge accumulation on -R-NH3+, and thus stronger Coulomb force of bond (-R-NH3+)-(PbBr42−), which facilitates excitons self-trapping. Our designed white perovskites exhibit photoluminescence quantum yield of 32%, color-rendering index of near 90 and chromaticity coordinates close to standard white-light. Our joint experiment-theory study provides insights into the STEs formation in perovskites and will benefit tailoring white perovskites with boosting performance.

Stimulating Efficient and Stable Ultralong Phosphorescence of 2D Perovskites by Dual-Mode Triplet Exciton Stabilization

“…The crystalline phase of the synthesized 2D perovskite materials is verified by powder X-ray diffraction (XRD) patterns (Figures b and S1). Along with the 4MPEACl organic salt, almost periodic diffraction peaks similar to that of the previously reported 2D perovskites are observed in 4MPPC without diffraction peak splitting . Specifically, the diffraction peaks exhibit a regular spacing assigned to the (002 l ) lattice planes, revealing the formation of a highly oriented layered 2D structure with high phase purity and crystallinity .…”

“…Along with the 4MPEACl organic salt, almost periodic diffraction peaks similar to that of the previously reported 2D perovskites are observed in 4MPPC without diffraction peak splitting. 35 Specifically, the diffraction peaks exhibit a regular spacing assigned to the (002l) lattice planes, revealing the formation of a highly oriented layered 2D structure with high phase purity and crystallinity. 36 The energy-dispersive spectroscopy mappings of 4MPPC suggest a uniform and continuous distribution of elements N, O, Pb, and Cl (Figure S2) with the Pb/Cl atom ratio approximated to 1:4.2, further confirming the formation of a 2D layered perovskite.…”

Metal halide perovskites-based white light-emitting diodes

“…efficiencies (EQEs) of more than 20% of green, red, and infrared light-emitting devices [30][31][32][33][34][35][36][37]. Moreover, recent studies have shown that metal halide perovskites have broadband emission or multi-color characteristic, which have demonstrated great potential in high-quality lighting applications [38][39][40].…”

Highly Stable and Moisture-Immune Monocomponent White Perovskite Phosphor by Trifluoromethyl (-CF3) Regulation

“…23 In general, perovskite powders or films are usually used in solid state lighting LEDs instead of single crystals. 20 Therefore, powders of 2-CF 3 , 3-CF 3 , and 4-CF 3 are prepared via the fast reprecipitation method 10 and named 2-CF 3 -P, 3-CF 3 -P, and 4-CF 3 -P, respectively. The experimental details are available in the Supporting Information.…”

“…Unfortunately, the self-absorption and unequal degradation of mixed-component phosphors will lead to obvious energy loss and discoloration, respectively. Recently, the development of monocomponent white lighting materials, including low-dimensional halide perovskites − and lead-free halide double perovskites, − has overcome these problems. Because of the large Stokes shift caused by self-trapped excitons (STEs), monocomponent white lighting materials exhibit intrinsic broadband white light emission without self-absorption and unequal degradation. − Since the first report on solid state white lighting using a two-dimensional halide perovskite (N-MEDA) [PbBr 4– x Cl x ] in 2014, halide perovskites have been intensively investigated due to their advantages of a diversified composition, facile synthesis, and solution processing.…”