Lee, EunjiDhakal, Krishna PrasadSong, HwayoungChoi, HeenangChung, Taek‐MoOh, SaeyoungYoung Jeong, HuMarmolejo‐Tejada, Juan M.Mosquera, Martín A.Loc Duong, DinhKang, KibumKim, Jeongyong2023-10-312023-10-312023-08Lee, E., Dhakal, K. P., Song, H., Choi, H., Chung, T.-M., Oh, S., Jeong, H. Y., Marmolejo-Tejada, J. M., Mosquera, M. A., Duong, D. L., Kang, K., Kim, J., Anomalous Temperature and Polarization Dependences of Photoluminescence of Metal-Organic Chemical Vapor Deposition-Grown GeSe2. Adv. Optical Mater. 2023, 2301355. https://doi.org/10.1002/adom.2023013552195-1071https://scholarworks.montana.edu/handle/1/18173This is the peer reviewed version of the following article: [Anomalous Temperature and Polarization Dependences of Photoluminescence of Metal‐Organic Chemical Vapor Deposition‐Grown GeSe2. Advanced Optical Materials (2023)], which has been published in final form at https://doi.org/10.1002/adom.202301355. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions: https://authorservices.wiley.com/author-resources/Journal-Authors/licensing/self-archiving.html#3.Germanium diselenide (GeSe2) is a 2D semiconductor with air stability, a wide bandgap, and anisotropic optical properties. The absorption and photoluminescence (PL) of single-crystalline 2D GeSe2 grown by metal-organic chemical vapor deposition and their dependence on temperature and polarization are studied. The PL spectra exhibit peaks at 2.5 eV (peak A) and 1.8 eV (peak B); peak A displays a strongly polarized emission along the short axis of the crystal, and peak B displays a weak polarization perpendicular to that of peak A. With increasing temperature, peak B shows anomalous behaviors, i.e., an increasing PL energy and intensity. The excitation energy-dependent PL, time-resolved PL, and density functional theory calculations suggest that peak A corresponds to the band-edge transition, whereas peak B originates from the inter-band mid-gap states caused by selenium vacancies passivated by oxygen atoms. The comprehensive study on the PL of single-crystalline GeSe2 sheds light on the origins of light emission in terms of the band structure of anisotropic GeSe2, making it beneficial for the corresponding optoelectronic applications.en-UScopyright Wiley 2023https://web.archive.org/web/20200106202133/https://onlinelibrary.wiley.com/library-info/products/price-listshttp://web.archive.org/web/20190530141919/https://authorservices.wiley.com/author-resources/Journal-Authors/licensing/self-archiving.htmlMOCVDGeSe2Se-vacancyphotoluminescencepolarization2D materialsArticle