Cesium Copper Iodide Perovskite Nanoscale-Thick Films with Tunable Photoluminescence for White Light-Emitting Diodes

Abstract

Cu-based halide perovskite derivatives (PDs) have emerged in recent years due to their low toxicity, high stability, and earth-abundant source. In particular, due to the special photophysical properties, such as broadband visible photoluminescence (PL), large Stokes shift, and high luminous efficiency, Cs−Cu−I PDs have attracted more attention in white light and short-wavelength light-emitting device applications. Here, Cs−Cu− I nanoscale-thick films with a mixed phase of CsCu 2 I 3 and Cs 3 Cu 2 I 5 are prepared by thermal evaporation. By adjusting the proportion of the evaporation source, different phase structures and tunable PL characteristics are realized. Subsequently, with a UV light-emitting diode (310 nm) as the excitation source, standard white emission with Commission International de l'Eclairage coordinates of (0.333, 0.338) is observed when the molar ratio of CsI and CuI powders is 0.75:1. Cs−Cu−I nanoscalethick films with excellent air stability might have promising potential applications in white lighting sources.

Work‐Function‐Tunable MXenes Electrodes to Optimize p‐CsCu2I3/n‐Ca2Nb3‐xTaxO10 Junction Photodetectors for Image Sensing and Logic Electronics

“…The p‐type perovskite CsCu 2 I 3 has a polycrystalline structure and high purity for the pattern fits well with the PDF#45‐0076. [ 36,37 ] Compared with the patterns of HCa 2 Nb 3 O 10 (PDF#40‐0884), [ 38 ] Ca 2 Nb 3‐ x Ta x O 10 also has high purity without a second phase. The high‐resolution XPS spectra of CsCu 2 I 3 and Ca 2 Nb 3‐ x Ta x O 10 are shown in Figure S9 (Supporting Information) to further describe their chemistry states.…”

“…The p-type perovskite CsCu 2 I 3 has a polycrystalline structure and high purity for the pattern fits well with the PDF#45-0076. [36,37] Compared with the patterns of HCa 2 Nb 3 O 10 (PDF#40-0884), [38] When using electrodes with lower work function on the CNTO side, such as MXene (work function = 4.9 eV), the Schottky barrier (1.17 eV) is supposed to be reduced. Thus, when the forward bias is applied across the whole p-n junction, the electron current from MXene to CNTO will be enlarged.…”

Photoluminescence and Raman Spectra of One-Dimensional Lead-free Perovskite CsCu2I3 Single-Crystal Wires

“…This claim was supported by the group’s first-principles calculations . This work has stirred up confusion in the community of researchers working on both applications and theory. , …”

“…18 This work has stirred up confusion in the community of researchers working on both applications and theory. 19,20 Raman spectroscopy is a sensitive and noninvasive optical technique for material characterization and identification. When utilized with PL, Raman spectroscopy offers a unique approach to understanding a material's optical properties through same-spot structure−property correlations and has resolved several controversies in optical properties of zero-and two-dimensional perovskites.…”

Highly emissive and color-tunable copper-based halide composites for bright white light-emitting diodes

“…Another disadvantage of this strategy is that it would bring about a change in the white-light emission color over time owing to the unequal degradation rates of the light emitters and the efficiency losses owing to the self-absorption effect. 34 Most recently, Li et al 35 prepared high-quality Cs-Cu-I nanoscale-thick films by thermal evaporation, and different proportions of phase structures corresponding to CsCu 2 I 3 and Cs 3 Cu 2 I 5 were realized by adjusting the molar ratios of CsI and CuI powders. Ma and co-workers 36 synthesized Cs 3 Cu 2 I 5 @-CsCu 2 I 3 composites by a one-step solution method and demonstrated high-performance WLEDs with a high color-rendering index (CRI) of 91.6 and an excellent operation stability.…”