Motivated by the technologically important spectral conversion of sunlight for efficient photocatalysis, we present a detailed analysis of the multicolor excitation of LiYF₄:Yb³⁺,Tm³⁺ nanocrystals leading to UV emission through upconversion. We demonstrate in particular that the combination of blue and IR light for generating upconversion UV emission is a linear mechanism that occurs at rather low density of excitation (a few mW/cm²). This upconversion efficiency is fully compatible with the broadband excitation from the sun, with comparable density similar to daylight excitation. It demonstrates that an appropriate design combining photocatalyst and a dedicated upconverter leads to a drastic improvement of the photocatalytic effect.

中文翻译：

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LiYF ₄：Yb ³⁺，Tm ³⁺纳米晶体中多色太阳吸收作为协同紫外上转换增强机理。

受用于有效光催化的技术上重要的太阳光谱转换的推动，我们对LiYF ₄：Yb ³⁺，Tm ³⁺纳米晶体的多色激发进行详细分析，从而通过上转换导致UV发射。我们特别证明，用于产生上转换UV发射的蓝光和IR光的组合是在相当低的激发密度（几mW / cm ²）下发生的线性机制。这种上转换效率与来自太阳的宽带激发完全兼容，其密度可与日光激发相媲美。它表明，将光催化剂和专用上变频器结合起来的适当设计可以显着提高光催化效果。