Colloidal CdSe quantum dots (QDs) are promising materials for solar cells because of their simple preparation process and compatibility with flexible substrates. The QD radiative recombination lifetime has attracted enormous attention as it affects the probability of photogenerated charges leaving the QDs and being collected at the battery electrodes. However, the scaling law for the exciton radiative lifetime in CdSe QDs is still a puzzle. This article presents a novel explanation that reconciles this controversy. Our calculations agree with the experimental measurements of all three divergent trends in a broadened energy window. Further, we proved that the exciton radiative lifetime is a consequence of the thermal average of decays for all thermally accessible exciton states. Each of the contradictory size-dependent patterns reflects this trend in a specific size range. As the optical band gap increases, the radiative lifetime decreases in larger QDs, increases in smaller QDs, and is weakly dependent on size in the intermediate energy region. This study addresses the inconsistencies in the scaling law of the exciton lifetime and gives a unified interpretation over a widened framework. Moreover, it provides valuable guidance for carrier separation in the thin film solar cell of CdSe QDs.Colloidal CdSe quantum dots (QDs) are promising materials for solar cells because of their simple preparation process and compatibility with flexible substrates. The QD radiative recombination lifetime has attracted enormous attention as it affects the probability of photogenerated charges leaving the QDs and being collected at the battery electrodes. However, the scaling law for the exciton radiative lifetime in CdSe QDs is still a puzzle. This article presents a novel explanation that reconciles this controversy. Our calculations agree with the experimental measurements of all three divergent trends in a broadened energy window. Further, we proved that the exciton radiative lifetime is a consequence of the thermal average of decays for all thermally accessible exciton states. Each of the contradictory size-dependent patterns reflects this trend in a specific size range. As the optical band gap increases, the radiative lifetime decreases in larger QDs, increases in smaller QDs, and is weakly dependent on size in the intermediate energy region. This study addresses the inconsistencies in the scaling law of the exciton lifetime and gives a unified interpretation over a widened framework. Moreover, it provides valuable guidance for carrier separation in the thin film solar cell of CdSe QDs.

为了缩小光谱仪体积使之适用于**卫星等领域，本文将胶体量子点作为滤光材料，研究了CdSe胶体量子点滤光片的光学特性。本文采用热注入法合成出了高质量的CdSe胶体量子点，经过对苯二胺消光处理制备成CdSe胶体量子点滤光片。利用透射电子显微镜（TEM）进行样品形貌结构的表征及粒径尺寸的测量，并分别在不同温度下进行了紫外-可见吸收测量和紫外-可见透过率测量。实验表明，在室温情况下，CdSe胶体量子点薄膜的吸收和透过率均随粒径尺寸的增加而增加；在给定粒径尺寸的情况下，CdSe胶体量子点薄膜吸收与透过率曲线的第一激子吸收峰峰位随温度升高发生红移，CdSe胶体量子点薄膜吸收曲线温度每增加10 K红移不超过1 nm，且半峰宽增加；此外，经反复实验验证CdSe胶体量子点滤光片的稳定性及可调谐特性，证实其适合作为截止滤光片。上述结果表明，CdSe 胶体量子点滤光片在微型光谱仪方面具有良好的应用价值。