新加坡南洋理工大学Assoc. Prof. Sum Tze Chien组新发现：

Slow Cooling and Highly Efficient Extraction of Hot-Carriers in Colloidal Perovskite Nanocrystals

钙钛矿型纳米晶中热载流子的缓慢冷却过程及高效提取

Scientific Achievement: Colloidal perovskite nanocrystals can overcome the limitations oftraditional inorganic quantum dots and achieve slow hot carrier cooling andefficient extraction. Our findings challenge the conventional wisdomestablished for traditional inorganic quantum dots. These perovskitenanocrystals exhibit around two orders slower hot-carrier cooling times andaround four times larger hot-carrier temperatures than their perovskitebulk-film counterparts. Efficienthot-electron extraction up to 83% in such systems was demonstrated.

科学成就：钙钛矿型纳米晶可以克服传统无机半导体量子点的某些缺陷，以达到热电子的缓慢冷却和高效提取。我们的发现向建立在传统无机量子点的普遍观念发起了挑战。相比较钙钛矿块体膜材料，这些钙钛矿纳米晶表现出约两个数量级长的热载流子冷却时间，和约四倍高的热载流子温度。在这种材料中实现了高达83%的热载流子提取效率。

Significance and Impact: Harvesting excess energy from above-bandgap photons could lead tosolar cells which exceed conventional efficiency limits. This approach can boostthe efficiency of perovskite solar cells to exceed their present 22% record byextracting the energy that is typically lost through heat. This can be achievedif the energetic (or hot-) charge carriers could be slowed down considerablyand efficiently extracted from the perovskite material. These insights enablefresh perspectives for the development of extremely thin absorber andconcentrator-type hot-carrier perovskite solar cells.

意义和影响：捕获高于半导体带隙的光子的能量会导致太阳能电池的效率超过传统的效率极限。通过提取这些一般由热能损耗掉的能量，能够推动钙钛矿型太阳能电池的效率超过其目前的22% 。要实现这种情况，在钙钛矿材料中需要缓慢冷却的热载流子以及高效的热载流子提取过程。我们的重要发现为开发钙钛矿超薄吸收层或聚合型热载流子太阳能电池提供了新的视角。

Research Details: Hot carrier cooling in hybrid perovskite materials with reduced dimensionality was investigated using transient absorption spectroscopy. Efficienthot-electron extraction up to 83% in surface-treated perovskite NCs thin films was demonstrated.

研究细节：用瞬态吸收光谱研究了低维度杂化钙钛矿半导体中热载流子的冷却过程。在表面修饰过的钙钛矿纳米晶薄膜中实现了高达83%的热载流子提取效率。

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