Yamada Yasuhiro, Oki Takeru, Morita Takeshi, Yamada Takumi, Fukuda Mitsuki, Ichikawa Shuhei, Kojima Kazunobu, Kanemitsu Yoshihiko
Graduate School of Science, Chiba University, Inage, Chiba 263-8522, Japan.
Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
Nano Lett. 2024 Sep 11;24(36):11255-11261. doi: 10.1021/acs.nanolett.4c02885. Epub 2024 Aug 29.
Highly efficient anti-Stokes (AS) photoluminescence (PL) is observed from halide perovskite quantum dots (QDs) due to their strong electron-phonon interactions. The AS PL is particularly intriguing, as it suggests the potential for semiconductor optical cooling if the external quantum efficiency approaches 100%. However, the PL quantum efficiency in QDs is primarily dominated by multiparticle nonradiative Auger recombination processes under intense photoexcitation, which impose limits on the optical cooling gain. Here, we investigate the Auger recombination of dot-in-crystal perovskites. We quantitatively estimate the maximum optical cooling gain and the corresponding excitation intensity. We further conducted optical cooling experiments and demonstrate a maximum photocooling of approximately 9 K from room temperature. Additionally, we confirmed that increasing the excitation intensity leads to a transition from photocooling to photoheating. These observations are consistent with our time-resolved measurements, offering insights into the potential and limitations of optical cooling in semiconductor QDs.
由于卤化物钙钛矿量子点（QDs）具有很强的电子-声子相互作用，因此观察到了高效的反斯托克斯（AS）光致发光（PL）。AS PL特别引人关注，因为如果外部量子效率接近100%，则表明半导体光学冷却具有潜力。然而，在强光激发下，量子点中的PL量子效率主要由多粒子非辐射俄歇复合过程主导，这对光学冷却增益施加了限制。在这里，我们研究了晶体中量子点钙钛矿的俄歇复合。我们定量估计了最大光学冷却增益和相应的激发强度。我们进一步进行了光学冷却实验，并证明从室温开始最大光冷却约为9K。此外，我们证实增加激发强度会导致从光冷却到光热的转变。这些观察结果与我们的时间分辨测量结果一致，为深入了解半导体量子点中光学冷却的潜力和局限性提供了依据。
