The utilization of solar energy by light conversion processes in both natural and artificial photosynthesis systems has become a pivotal means of sustaining a consistent power supply for our daily lives and production. In general, these reactions rely on the visible spectra region where the sun produces abundant energy according to the black body's emission. Further expanding the adoption of the near-infrared (NIR) spectral region through upconversion has become an intelligent strategy to improve the entire utilization rate of solar energy. In this work, the two-photon upconversion (TPUC) properties were discovered in CsPbBr3 nanoplates (NPs) emitted at 450 nm, and a sub-gap energy level was observed to serve as the center to facilitate the upconversion process. The excitation threshold for TPUC is drastically lower than that for the two-photon absorption, another nonlinear upconversion path that requires strengthened excitation power. Moreover, a significant negative correlation between the excitation threshold for TPUC in the CsPbBr3 NPs and the exciton binding energy was unveiled, which could be attributed to the enhanced quantum confinement effects. Our work paved the way for a feasible way to expand the utilization of the NIR spectral region in light conversion applications.

中文翻译：

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CsPbBr3 纳米板中的双光子上转换光致发光


在自然和人工光合作用系统中，通过光转换过程对太阳能的利用已成为为我们的日常生活和生产维持稳定电力供应的关键手段。一般来说，这些反应依赖于可见光谱区域，太阳根据黑体的发射产生丰富的能量。通过上转换进一步扩大近红外 （NIR） 光谱区域的采用已成为提高太阳能整体利用率的智能策略。在这项工作中，在 450 nm 发射的 CsPbBr3 纳米板 （NPs） 中发现了双光子上转换 （TPUC） 特性，并观察到亚间隙能级作为促进上转换过程的中心。TPUC 的激发阈值大大低于双光子吸收的激发阈值，这是另一种需要增强激发功率的非线性上转换路径。此外，揭示了 CsPbBr3 NPs 中 TPUC 的激发阈值与激子结合能之间存在显着的负相关关系，这可能归因于增强的量子限制效应。我们的工作为扩大 NIR 光谱区域在光转换应用中的利用铺平了道路。