Abstract The ability to precisely measure temperature is critical to eventually developing semiconductor-based optical refrigerators. Presently, a number of approaches exist for conducting contactless temperature measurements. They are mainly based on the temperature-dependent optical response of materials. A common approach called pump–probe luminescence thermometry (PPLT) uses temperature-dependent shifts of a material’s band edge emission energy to assess temperature. PPLT, however, cannot be reliably applied to materials such as CsPbBr 3 nanocrystals, which exhibit temperature insensitive band gaps. To overcome this restriction, we have developed a new optical thermometry based on temperature-dependent changes to below gap-excited (anti-Stokes, ASPL) and above gap-excited (Stokes, PL) photoluminescence intensity ratios (i.e. I ASPL / I PL ). In it, I ASPL / I PL can be used to assess local temperature due to the exponentially sensitive nature of emission up-conversion efficiencies. The developed thermometry is not unique to CsPbBr 3 and can be applied other systems found suitable for demonstrating semiconductor-based laser cooling.

中文翻译：

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用于半导体激光器冷却的上转换发射测温

摘要 精确测量温度的能力对于最终开发基于半导体的光学制冷机至关重要。目前，存在许多用于进行非接触式温度测量的方法。它们主要基于材料的温度相关光学响应。一种称为泵浦-探针发光测温 (PPLT) 的常用方法使用材料带边发射能量的温度相关偏移来评估温度。然而，PPLT 不能可靠地应用于诸如 CsPbBr 3 纳米晶体之类的材料，这些材料表现出对温度不敏感的带隙。为了克服这一限制，我们开发了一种新的光学温度计，它基于温度相关变化到低于间隙激发（反斯托克斯，ASPL）和高于间隙激发（斯托克斯，PL）的光致发光强度比（即 I ASPL / I PL ）。其中，I ASPL / I PL 可用于评估局部温度，因为发射上转换效率的指数敏感性。所开发的温度计并非 CsPbBr 3 独有，可以应用于其他适合演示基于半导体的激光冷却的系统。