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arXiv · 2411.12463

Micrometer-resolution fluorescence and lifetime mappings of CsPbBr$_3$ nanocrystal films coupled with a TiO$_2$ grating

Viet Anh Nguyen·Linh Thi Dieu Nguyen·Thi Thu Ha Do·Ye Wu·Aleksandr A. Sergeev·Ding Zhu·Vytautas Valuckas·Duong Pham·Hai Xuan Son Bui·Duy Mai Hoang·Son Tung Bui·Xuan Khuyen Bui·Binh Thanh Nguyen·Hai Son Nguyen·Lam Dinh Vu·Andrey Rogach·Son Tung Ha·Quynh Le-Van
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Abstract

Enhancing light emission from perovskite nanocrystal (NC) films is essential in light-emitting devices, as their conventional stacks often restrict the escape of emitted light. This work addresses this challenge by employing a TiO$_2$ grating to enhance light extraction and shape the emission of CsPbBr$_3$ nanocrystal films. Angle-resolved photoluminescence (PL) demonstrated a tenfold increase in emission intensity by coupling the Bloch resonances of the grating with the spontaneous emission of the perovskite NCs. Fluorescence lifetime imaging microscopy (FLIM) provided micrometer-resolution mapping of both PL intensity and lifetime across a large area, revealing a decrease in PL lifetime from 8.2 ns for NC films on glass to 6.1 ns on the TiO$_2$ grating. Back focal plane (BFP) spectroscopy confirmed how the Bloch resonances transformed the unpolarized, spatially incoherent emission of NCs into polarized and directed light. These findings provide further insights into the interactions between dielectric nanostructures and perovskite NC films, offering possible pathways for designing better performing perovskite optoelectronic devices.

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Viet Anh Nguyen, Linh Thi Dieu Nguyen, Thi Thu Ha Do, Ye Wu, Aleksandr A. Sergeev, Ding Zhu, Vytautas Valuckas, Duong Pham, Hai Xuan Son Bui, Duy Mai Hoang, Son Tung Bui, Xuan Khuyen Bui, Binh Thanh Nguyen, Hai Son Nguyen, Lam Dinh Vu, Andrey Rogach, Son Tung Ha, Quynh Le-Van. 2024-11-19. Micrometer-resolution fluorescence and lifetime mappings of CsPbBr$_3$ nanocrystal films coupled with a TiO$_2$ grating. https://doi.org/10.1021/acs.jpclett.4c02546

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