Yang Bin, Chen Junsheng, Yang Songqiu, Hong Feng, Sun Lei, Han Peigeng, Pullerits Tõnu, Deng Weiqiao, Han Keli
State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian, 116023, P. R. China.
University of the Chinese Academy of Sciences, Beijing, 100039, P. R. China.
Angew Chem Int Ed Engl. 2018 May 4;57(19):5359-5363. doi: 10.1002/anie.201800660. Epub 2018 Mar 26.
Lead-free perovskite nanocrystals (NCs) were obtained mainly by substituting a Pb cation with a divalent cation or substituting three Pb cations with two trivalent cations. The substitution of two Pb cations with one monovalent Ag and one trivalent Bi cations was used to synthesize Cs AgBiX (X=Cl, Br, I) double perovskite NCs. Using femtosecond transient absorption spectroscopy, the charge carrier relaxation mechanism was elucidated in the double perovskite NCs. The Cs AgBiBr NCs exhibit ultrafast hot-carrier cooling (<1 ps), which competes with the carrier trapping processes (mainly originate from the surface defects). Notably, the photoluminescence can be increased by 100 times with surfactant (oleic acid) added to passivate the defects in Cs AgBiCl NCs. These results suggest that the double perovskite NCs could be potential materials for optoelectronic applications by better controlling the surface defects.
无铅钙钛矿纳米晶体（NCs）主要通过用二价阳离子取代Pb阳离子或用两个三价阳离子取代三个Pb阳离子来获得。用一个单价Ag和一个三价Bi阳离子取代两个Pb阳离子用于合成Cs AgBiX（X = Cl、Br、I）双钙钛矿NCs。利用飞秒瞬态吸收光谱，阐明了双钙钛矿NCs中的电荷载流子弛豫机制。Cs AgBiBr NCs表现出超快的热载流子冷却（<1 ps），这与载流子俘获过程（主要源于表面缺陷）相互竞争。值得注意的是，在Cs AgBiCl NCs中添加表面活性剂（油酸）以钝化缺陷，光致发光可提高100倍。这些结果表明，通过更好地控制表面缺陷，双钙钛矿NCs可能成为光电子应用的潜在材料。
