Contracted, Not Converted: Photoluminescence Thermochromism in Ultrabright Pure Blue Emissive Hybrid Copper(I) Halide

Dilruba A. Popy; Lauren M. Loftus; Jie Jiang; Jeffrey D. Einkauf; Suryaveer Kapoor; Michael A. McGuire; Ruth Pachter; Bayram Saparov

doi:10.1002/smll.202506916

Contracted, Not Converted: Photoluminescence Thermochromism in Ultrabright Pure Blue Emissive Hybrid Copper(I) Halide

Dilruba A. Popy
, Lauren M. Loftus
, Jie Jiang
, Jeffrey D. Einkauf
, Suryaveer Kapoor
, Michael A. McGuire
, Ruth Pachter
, Bayram Saparov

Research output: Contribution to journal › Article › peer-review

1 Scopus citations

Abstract

Thermochromic luminescent materials are promising for applications such as sensors or display technologies. Understanding the mechanism of thermochromic luminescence in these materials plays an important role for their targeted applications. Here, a 0D copper(I) halide (TMP)₂CuBr₃ and 1D (TMP)Ag₂Br₃ (TMP = tetramethylphosphonium) are reported. While (TMP)Ag₂Br₃ is a weak light emitter, (TMP)₂CuBr₃ demonstrates ultrabright pure blue emission with photoluminescence (PL) quantum yield exceeding 90% within the temperature range 300–80 K. The emission in (TMP)₂CuBr₃ is attributed to the radiative recombination of self-trapped excitons (STEs) that arise localized on [CuBr₃]²⁻ anions. (TMP)₂CuBr₃ demonstrates excitation-selective PL thermochromism at low temperatures. In the literature, the origin of multiple STEs is often unclear in luminescent metal halides. Here, a detailed temperature-dependent spectroscopic and structural analysis suggests that the PL thermochromism in (TMP)₂CuBr₃ is associated with the appearance of a second STE state. The appearance of second STE is expected to have a structural origin, and it may be associated with the observed anomaly in thermal contraction near 200 K. The distinct PL features of melt-processible (TMP)₂CuBr₃ coupled with its remarkable photo- and thermal stability allow its consideration for practical optical applications, including temperature sensing.

Original language	English
Article number	e06916
Journal	Small
Volume	21
Issue number	38
DOIs	https://doi.org/10.1002/smll.202506916
State	Published - Sep 25 2025

Funding

This work was supported by the National Science Foundation (Grant No. NSF DMR-2045490). Low temperature powder X-ray diffraction measurements at Oak Ridge National Laboratory were supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. L.M.L. would also like to acknowledge funding under AFRL/RXEP Contract No. FA8650-22-F-5408. J.D.E. acknowledges support from the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division (Grant No. DE-SC00ERKCC08). This work was supported by the National Science Foundation (Grant No. NSF DMR‐2045490). Low temperature powder X‐ray diffraction measurements at Oak Ridge National Laboratory were supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. L.M.L. would also like to acknowledge funding under AFRL/RXEP Contract No. FA8650‐22‐F‐5408. J.D.E. acknowledges support from the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division (Grant No. DE‐SC00ERKCC08).

Keywords

blue emission
luminescence thermochromism
metal halides
perovskite
semiconductors

Access to Document

10.1002/smll.202506916

Cite this

@article{4ab9886f4aef4fb2bd7f3b04c966a576,

title = "Contracted, Not Converted: Photoluminescence Thermochromism in Ultrabright Pure Blue Emissive Hybrid Copper(I) Halide",

abstract = "Thermochromic luminescent materials are promising for applications such as sensors or display technologies. Understanding the mechanism of thermochromic luminescence in these materials plays an important role for their targeted applications. Here, a 0D copper(I) halide (TMP)2CuBr3 and 1D (TMP)Ag2Br3 (TMP = tetramethylphosphonium) are reported. While (TMP)Ag2Br3 is a weak light emitter, (TMP)2CuBr3 demonstrates ultrabright pure blue emission with photoluminescence (PL) quantum yield exceeding 90\% within the temperature range 300–80 K. The emission in (TMP)2CuBr3 is attributed to the radiative recombination of self-trapped excitons (STEs) that arise localized on [CuBr3]2− anions. (TMP)2CuBr3 demonstrates excitation-selective PL thermochromism at low temperatures. In the literature, the origin of multiple STEs is often unclear in luminescent metal halides. Here, a detailed temperature-dependent spectroscopic and structural analysis suggests that the PL thermochromism in (TMP)2CuBr3 is associated with the appearance of a second STE state. The appearance of second STE is expected to have a structural origin, and it may be associated with the observed anomaly in thermal contraction near 200 K. The distinct PL features of melt-processible (TMP)2CuBr3 coupled with its remarkable photo- and thermal stability allow its consideration for practical optical applications, including temperature sensing.",

keywords = "blue emission, luminescence thermochromism, metal halides, perovskite, semiconductors",

author = "Popy, \{Dilruba A.\} and Loftus, \{Lauren M.\} and Jie Jiang and Einkauf, \{Jeffrey D.\} and Suryaveer Kapoor and McGuire, \{Michael A.\} and Ruth Pachter and Bayram Saparov",

note = "Publisher Copyright: {\textcopyright} 2025 Wiley-VCH GmbH.",

year = "2025",

month = sep,

day = "25",

doi = "10.1002/smll.202506916",

language = "English",

volume = "21",

journal = "Small",

issn = "1613-6810",

publisher = "wiley",

number = "38",

}

TY - JOUR

T1 - Contracted, Not Converted

T2 - Photoluminescence Thermochromism in Ultrabright Pure Blue Emissive Hybrid Copper(I) Halide

AU - Popy, Dilruba A.

AU - Loftus, Lauren M.

AU - Jiang, Jie

AU - Einkauf, Jeffrey D.

AU - Kapoor, Suryaveer

AU - McGuire, Michael A.

AU - Pachter, Ruth

AU - Saparov, Bayram

PY - 2025/9/25

Y1 - 2025/9/25

N2 - Thermochromic luminescent materials are promising for applications such as sensors or display technologies. Understanding the mechanism of thermochromic luminescence in these materials plays an important role for their targeted applications. Here, a 0D copper(I) halide (TMP)2CuBr3 and 1D (TMP)Ag2Br3 (TMP = tetramethylphosphonium) are reported. While (TMP)Ag2Br3 is a weak light emitter, (TMP)2CuBr3 demonstrates ultrabright pure blue emission with photoluminescence (PL) quantum yield exceeding 90% within the temperature range 300–80 K. The emission in (TMP)2CuBr3 is attributed to the radiative recombination of self-trapped excitons (STEs) that arise localized on [CuBr3]2− anions. (TMP)2CuBr3 demonstrates excitation-selective PL thermochromism at low temperatures. In the literature, the origin of multiple STEs is often unclear in luminescent metal halides. Here, a detailed temperature-dependent spectroscopic and structural analysis suggests that the PL thermochromism in (TMP)2CuBr3 is associated with the appearance of a second STE state. The appearance of second STE is expected to have a structural origin, and it may be associated with the observed anomaly in thermal contraction near 200 K. The distinct PL features of melt-processible (TMP)2CuBr3 coupled with its remarkable photo- and thermal stability allow its consideration for practical optical applications, including temperature sensing.

AB - Thermochromic luminescent materials are promising for applications such as sensors or display technologies. Understanding the mechanism of thermochromic luminescence in these materials plays an important role for their targeted applications. Here, a 0D copper(I) halide (TMP)2CuBr3 and 1D (TMP)Ag2Br3 (TMP = tetramethylphosphonium) are reported. While (TMP)Ag2Br3 is a weak light emitter, (TMP)2CuBr3 demonstrates ultrabright pure blue emission with photoluminescence (PL) quantum yield exceeding 90% within the temperature range 300–80 K. The emission in (TMP)2CuBr3 is attributed to the radiative recombination of self-trapped excitons (STEs) that arise localized on [CuBr3]2− anions. (TMP)2CuBr3 demonstrates excitation-selective PL thermochromism at low temperatures. In the literature, the origin of multiple STEs is often unclear in luminescent metal halides. Here, a detailed temperature-dependent spectroscopic and structural analysis suggests that the PL thermochromism in (TMP)2CuBr3 is associated with the appearance of a second STE state. The appearance of second STE is expected to have a structural origin, and it may be associated with the observed anomaly in thermal contraction near 200 K. The distinct PL features of melt-processible (TMP)2CuBr3 coupled with its remarkable photo- and thermal stability allow its consideration for practical optical applications, including temperature sensing.

KW - blue emission

KW - luminescence thermochromism

KW - metal halides

KW - perovskite

KW - semiconductors

UR - https://www.scopus.com/pages/publications/105012596598

U2 - 10.1002/smll.202506916

DO - 10.1002/smll.202506916

M3 - Article

C2 - 40772343

AN - SCOPUS:105012596598

SN - 1613-6810

VL - 21

JO - Small

JF - Small

IS - 38

M1 - e06916

ER -

Contracted, Not Converted: Photoluminescence Thermochromism in Ultrabright Pure Blue Emissive Hybrid Copper(I) Halide

Abstract

Funding

Keywords

Access to Document

Other files and links

Fingerprint

Cite this