Organic–Inorganic Hybrid Cuprous‐Based Metal Halides for Warm White Light‐Emitting Diodes

Abstract

Single-component emitters with stable and bright warm white-light emission are highly desirable for high-efficacy warm white light-emitting diodes (warm-WLEDs), however, materials with such luminescence properties are extremely rare. Lowdimensional lead (Pb) halide perovskites can achieve warm white photoluminescence (PL), yet they suffer from low stability and PL quantum yield (PLQY). While Pb-free air-stable perovskites such as Cs 2 AgInCl 6 emit desirable warm white light, sophisticated doping strategies are typically required to increase their PL intensity. Moreover, the use of rare metal-bearing compounds along with the typically required vacuum-based thin-film processing may greatly increase their production cost. Herein, organic-inorganic hybrid cuprous (Cu + )-based metal halide MA 2 CuCl 3 (MA = CH 3 NH 3 + ) that meets the requirements of i) nontoxicity, ii) high PLQY, and iii) dopant-free is presented. Both single crystals and thin films of MA 2 CuCl 3 can be facilely prepared by a low-cost solution method, which demonstrate bright warm white-light emission with intrinsically high PLQYs of 90-97%. Prototype electroluminescence devices and down-conversion LEDs are fabricated with MA 2 CuCl 3 thin films and single crystals, respectively, which show bright luminescence with decent efficiencies and operational stability. These findings suggest that MA 2 CuCl 3 has a great potential for the single-component indoor lighting and display applications.

Blue photoluminescence enhancement achieved by zero-dimensional organic indium halidesviaa metal ion doping strategy

“…S6 (ESI †), (MA) 4 InCl 7 , (MA) 4 InCl 7 :Cs + and (MA) 4 InCl 7 :Mn 2+ exhibit various degrees of Urbach tails which indicate that there are a certain number of sub-band-gap states underneath the conduction band of each structure upon photoexcitation, which could be the result of defects, structural disorders or inhomogeneity of crystals. [47][48][49][50][51] When passivated by Cs + and Mn 2+ , the sub-bandgap states of (MA) 4 InCl 7 should partially diminished, explaining the reduced FWHM and increased PLQE. A very small Urbach tail was observed for (MA) 4 InCl 7 :Sb 3+ , suggesting minimized sub-band-gap states and homogenous crystals with less defects.…”

Colloidal synthesis of size-confined CsAgCl2 nanocrystals: implications for electroluminescence applications

“…The LED turns on at a voltage of 16.0 V (corresponding to a luminance of 1 cd m À2 ) with a maximum luminance up to 9.6 cd m À2 and an EQE of 0.02%. We note that such a luminous efficiency is lower than those of 3D CsAgIn 0.9 Bi 0.1 Cl 6 -based LEDs (maximum EQE B0.08%) and our recently developed MA 2 CuCl 3 warm white LEDs (B0.04%), 5,10 which points to the fact that our LEDs still suffer from significant injection barriers and/or charge injection imbalance, partially due to the low carrier mobility of CsAgCl 2 because of its 0D crystal structure at the molecular level. In addition to a better device design, we foresee that the EL performance can be further increased by enhancing the PLQY of these CsAgCl 2 NCs because the maximum value of the yield currently achievable for NC thin films is only 30%.…”

“…Lead (Pb)-free metal halide perovskites and their derivatives have drawn tremendous interest for many emerging applications because of their benefits of reduced toxicity and possibilities of broadband white-light emission, which is enabled by their self-trapped excitons (STEs). [1][2][3][4][5] Recently, these materials were extensively studied in the form of nanocrystals (NCs) and used as potential candidates for light-emitting diodes (LEDs) owing to their high photoluminescence quantum yields (PLQYs) and high compatibility with low-cost solution-based processes. The merits of rendering the emitters in the form of NCs include the versatile colloidal syntheses, which allow a facile surface modification of the semiconductors via organic ligands and hence enable a higher PLQY.…”

Tailoring the high-brightness “warm” white light emission of two-dimensional perovskite crystalsviaa pressure-inhibited nonradiative transition

“…5b), resulting in a further significant enhancement of the PL of the (2meptH 2 )PbCl 4 crystal until 9.9 GPa. 48,49 At pressures above 9.9 GPa, the distortion of the sample intensifies and the disordered stage starts, thus inhibiting the radiative recombination and promoting the nonradiative transition, and the PL begins to weaken at this time. In addition, the shape of the PL spectra always maintains obvious symmetry, indicating that multiple STE states with broad emission coexist well in equilibrium.…”