Liu Maning, Pasanen Hannu, Ali-Löytty Harri, Hiltunen Arto, Lahtonen Kimmo, Qudsia Syeda, Smått Jan-Henrik, Valden Mika, Tkachenko Nikolai V, Vivo Paola
Chemistry and Advanced Materials Group, Faculty of Engineering and Natural Sciences, Tampere University, P.O. Box 692, 33014, Tampere, Finland.
Surface Science Group, Faculty of Engineering and Natural Sciences, Tampere University, P.O. Box 692, 33014, Tampere, Finland.
Angew Chem Int Ed Engl. 2020 Dec 1;59(49):22117-22125. doi: 10.1002/anie.202008724. Epub 2020 Sep 25.
Colloidal lead-free perovskite nanocrystals have recently received extensive attention because of their facile synthesis, the outstanding size-tunable optoelectronic properties, and less or no toxicity in their commercial applications. Tin (Sn) has so far led to the most efficient lead-free solar cells, yet showing highly unstable characteristics in ambient conditions. Here, we propose the synthesis of all-inorganic mixture Sn-Ge perovskite nanocrystals, demonstrating the role of Ge in stabilizing Sn cation while enhancing the optical and photophysical properties. The partial replacement of Sn atoms by Ge atoms in the nanostructures effectively fills the high density of Sn vacancies, reducing the surface traps and leading to a longer excitonic lifetime and increased photoluminescence quantum yield. The resultant Sn-Ge nanocrystals-based devices show the highest efficiency of 4.9 %, enhanced by nearly 60 % compared to that of pure Sn nanocrystals-based devices.
胶体无铅钙钛矿纳米晶体因其易于合成、出色的尺寸可调光电特性以及在商业应用中低毒或无毒，最近受到了广泛关注。到目前为止，锡（Sn）已带来了最有效的无铅太阳能电池，但在环境条件下表现出高度不稳定的特性。在此，我们提出合成全无机混合Sn-Ge钙钛矿纳米晶体，证明了Ge在稳定Sn阳离子的同时增强光学和光物理性质方面的作用。在纳米结构中用Ge原子部分替代Sn原子有效地填充了高密度的Sn空位，减少了表面陷阱，导致激子寿命更长，光致发光量子产率增加。所得基于Sn-Ge纳米晶体的器件显示出最高4.9%的效率，与基于纯Sn纳米晶体的器件相比提高了近60%。
