All‐inorganic copper(I) halides have recently emerged as attractive alternatives to lead‐based halide perovskites and rare‐earth‐doped inorganics for light emission applications. Most of the newly discovered all‐inorganic Cu(I) halides demonstrate high‐efficiency blue emission albeit with unusually poor tunability of photoluminescence (PL) properties. This work reports the facile preparation of three new copper(I) halides based on the guanidinium cation: (CN3H6)3CuCl4, (CN3H6)7Cu3Br10·3(C3H7NO), and (CN3H6)7Cu3I10·3(C3H7NO). A comprehensive characterization of PL is presented for these novel materials, which have highly tunable, dual blue–yellow emission responsive to both excitation wavelength and vacuum annealing. These have remarkable photoluminescence quantum yield (PLQY) values of up to 34.6% and color‐rendering indices (CRI) up to 97% for tunable, single‐phase white light emission with correlated color temperatures (CCT) ranging from 4851 to 18 921 K, demonstrating the excellent potential of Cu(I) halides for light emission applications.
Vapor-Phase Growth of CsPbBr 3 Microstructures for Highly Efficient Pure Green Light Emission
All-inorganic lead halide perovskites have been extensively studied in the past
several years due to their superior stability against moisture, oxygen, light,
and heat compared with their organic–inorganic counterparts. CsPbBr3 with
suitable band gap and ultrahigh photoluminescence quantum yield is a promising
candidate for pure green emitter in the backlighting display to fill the
so-called “green gap.” Here, vapor-phase growth of CsPbBr3 microspheres
is reported for highly efficient pure green light emission. The as-synthesized
microspheres exhibit a stronger photoluminescence (PL) intensity with a
photoluminescence quantum yield of 75% resulting from the lower energy
of longitudinal optical phonons revealed by temperature dependent PL
studies. Importantly, with the diameter increasing from 2 to 50 μm the PL
peak positions of the microspheres can be readily tuned from 527 to 539 nm,
well filling the so-called “green gap.” The red-shift with increasing diameter
can be ascribed to the reabsorption process during the photon propagation
inside the microspheres. The studies provide a route to improve the photoluminescence quantum yield in all-inorganic lead halide perovskites, but also
suggest an alternative approach to achieve the pure green emission for the
backlighting display.
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- Award ID(s):
- 1301346
- NSF-PAR ID:
- 10083359
- Date Published:
- Journal Name:
- Advanced Optical Materials
- ISSN:
- 2195-1071
- Page Range / eLocation ID:
- 1801336
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Copper(I) halides are emerging as attractive alternatives to lead halide perovskites for optical and electronic applications. However, blue‐emitting all‐inorganic copper(I) halides suffer from poor stability and lack of tunability of their photoluminescence (PL) properties. Here, the preparation of silver(I) halides A2AgX3(A = Rb, Cs; X = Cl, Br, I) through solid‐state synthesis is reported. In contrast to the Cu(I) analogs, A2AgX3are broad‐band emitters sensitive to A and X site substitutions. First‐principle calculations show that defect‐bound excitons are responsible for the observed main PL peaks in Rb2AgX3and that self‐trapped excitons (STEs) contribute to a minor PL peak in Rb2AgBr3. This is in sharp contrast to Rb2CuX3, in which the PL is dominated by the emission by STEs. Moreover, the replacement of Cu(I) with Ag(I) in A2AgX3significantly improves photostability and stability in the air under ambient conditions, which enables their consideration for practical applications. Thus, luminescent inks based on A2AgX3are prepared and successfully used in anti‐counterfeiting applications. The excellent light emission properties, significantly improved stability, simple preparation method, and tunable light emission properties demonstrated by A2AgX3suggest that silver(I) halides may be attractive alternatives to toxic lead halide perovskites and unstable copper(I) halides for optical applications.
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1002/adom.201801336
