The all-inorganic perovskite nanocrystals are currently in the research spotlight owing to their physical stability and superior optical properties-these features make them interesting for optoelectronic and photovoltaic applications. Here, we report on the observation of highly efficient carrier multiplication in colloidal CsPbI₃ nanocrystals prepared by a hot-injection method. The carrier multiplication process counteracts thermalization of hot carriers and as such provides the potential to increase the conversion efficiency of solar cells. We demonstrate that carrier multiplication commences at the threshold excitation energy near the energy conservation limit of twice the band gap, and has step-like characteristics with an extremely high quantum yield of up to 98%. Using ultrahigh temporal resolution, we show that carrier multiplication induces a longer build-up of the free carrier concentration, thus providing important insights into the physical mechanism responsible for this phenomenon. The evidence is obtained using three independent experimental approaches, and is conclusive.

中文翻译：

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CsPbI3钙钛矿纳米晶体中的有效载流子增殖。

全无机钙钛矿纳米晶体由于其物理稳定性和优异的光学性能，目前正成为研究的热点。这些特性使它们对于光电和光伏应用很有趣。在这里，我们报告在胶体CsPbI _3中高效载子增殖的观察通过热注射方法制备的纳米晶体。载流子倍增过程抵消了热载流子的热化，因此提供了提高太阳能电池转换效率的潜力。我们证明，载流子的增殖从阈值激发能开始，接近于带隙两倍的能量守恒极限，并具有阶梯状的特征，量子产率高达98％。使用超高的时间分辨率，我们表明载流子的繁殖诱导了更长的自由载流子浓度的积累，从而为造成这种现象的物理机制提供了重要的见识。证据是使用三种独立的实验方法获得的，并且是结论性的。