Extrinsic Green Photoluminescence from the Edges of 2D Cesium Lead Halides

Journal Article · 23 June 2019 · Advanced Materials

DOI: https://doi.org/10.1002/adma.201902492 · OSTI ID:1557010

Wang, Chong ^[1]; Wang, Yanan ^[2]; Su, Xinghua ^[3]; Hadjiev, Viktor G. ^[4]; Dai, Shenyu ^[5]; Qin, Zhaojun ^[2]; Calderon Benavides, Hector A. ^[6]; Ni, Yizhou ^[7]; Li, Qiang ^[8]; Jian, Jie ^[8]; Alam, Md. Kamrul ^[9]; Wang, Haiyan ^[8]; Robles Hernandez, Francisco C. ^[10]; Yao, Yan ^[11]; Chen, Shuo ^[7]; Yu, Qingkai ^[12]; Feng, Guoying ^[13]; Wang, Zhiming ^[14]; Bao, Jiming  ^[15]

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1. School of Materials Science and Engineering Yunnan University Kunming Yunnan 650500 China, Department of Electrical and Computer Engineering University of Houston Houston TX 77204 USA
2. Department of Electrical and Computer Engineering University of Houston Houston TX 77204 USA, Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of China Chengdu Sichuan 610054 China
3. Department of Electrical and Computer Engineering University of Houston Houston TX 77204 USA, School of Materials Science and Engineering Chang'an University Xi'an Shaanxi 710061 China
4. Texas Center for Superconductivity University of Houston Houston TX 77204 USA, Department of Mechanical Engineering University of Houston Houston TX 77204 USA
5. Department of Electrical and Computer Engineering University of Houston Houston TX 77204 USA, College of Electronics and Information Engineering Sichuan University Chengdu Sichuan 610064 China
6. Instituto Politecnico Nacional ESFM‐IPN UPALM Departamento de Física Mexico CDMX 07338 Mexico
7. Texas Center for Superconductivity University of Houston Houston TX 77204 USA, Department of Physics University of Houston Houston TX 77204 USA
8. Department of Materials Engineering Purdue University West Lafayette IN 47907 USA
9. Materials Science and Engineering University of Houston Houston TX 77204 USA
10. Department of Electrical and Computer Engineering University of Houston Houston TX 77204 USA, Mechanical Engineering Technology University of Houston Houston TX 77204 USA
11. Department of Electrical and Computer Engineering University of Houston Houston TX 77204 USA, Texas Center for Superconductivity University of Houston Houston TX 77204 USA, Materials Science and Engineering University of Houston Houston TX 77204 USA
12. Ingram School of Engineering Texas State University San Marcos TX 78666 USA
13. College of Electronics and Information Engineering Sichuan University Chengdu Sichuan 610064 China
14. Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of China Chengdu Sichuan 610054 China
15. Department of Electrical and Computer Engineering University of Houston Houston TX 77204 USA, Materials Science and Engineering University of Houston Houston TX 77204 USA

Abstract Since the first report of the green emission of 2D all‐inorganic CsPb ₂ Br ₅ , its bandgap and photoluminescence (PL) origin have generated intense debate and remained controversial. After the discovery that PL centers occupy only specific morphological structures in CsPb ₂ Br ₅ , a two‐step highly sensitive and noninvasive optical technique is employed to resolve the controversy. Same‐spot Raman‐PL as a static property–structure probe reveals that CsPbBr ₃ nanocrystals are contributing to the green emission of CsPb ₂ Br ₅ ; pressure‐dependent Raman‐PL with a diamond anvil cell as a dynamic probe further rules out point defects such as Br vacancies as an alternative mechanism. Optical absorption under hydrostatic pressure shows that the bandgap of CsPb ₂ Br ₅ is 0.3–0.4 eV higher than previously reported values and remains nearly constant with pressure up to 2 GPa in good agreement with full‐fledged density functional theory (DFT) calculations. Using ion exchange of Br with Cl and I, it is further proved that CsPbBr _{3− x} X _x (X = Cl or I) is responsible for the strong visible PL in CsPb ₂ Br _{5− x} X _x . This experimental approach is applicable to all PL‐active materials to distinguish intrinsic defects from extrinsic nanocrystals, and the findings pave the way for new design and development of highly efficient optoelectronic devices based on all‐inorganic lead halides.

• Sponsoring Organization: USDOE
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 1557010
• Journal Information: Advanced Materials, Journal Name: Advanced Materials Journal Issue: 33 Vol. 31; ISSN 0935-9648
• Publisher: Wiley Blackwell (John Wiley & Sons)Copyright Statement
• Country of Publication: Germany
• Language: English