Journal of Nanoparticle Research ( IF 2.1 ) Pub Date : 2021-09-08 , DOI: 10.1007/s11051-021-05324-z Ramakrishnan Jayakrishnan 1 , Ramesh Chandran 1 , Aruna R. Raj 1 , Sreekanth J. Varma 2
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We have used ligand-assisted re-precipitation (LARP) technique to grow colloidal nano-platelets of Cu-doped cesium lead bromide (CsPbBr3) perovskite in room ambient. Using selected-area diffraction and transmission electron microscopy, the structure of the nano-crystals was identified to be the orthorhombic crystal phase. From green emission (520 nm) for the un-doped CsPbBr3 nano-crystals, we were able to shift the emission to blue (464 nm) for the 1% doped CsPbBr3 nano-platelets. As the doping concentration was increased, the edge length of nano-platelets increased and resulted in a decrease in the Stokes shift. Optical band gap was found to increase from 2.6 eV for the un-doped CsPbBr3 to 2.81 eV for the 2% doped sample. We report that the formation of excitons with binding energy in the regime 70–110 meV is responsible for the blue photoluminescence. The green emissions have been identified to be due to defect levels located at 210–380 meV below the conduction band edge. The PLE peaks exhibit no shift with increasing excitation wavelength signifying quantum confinement effect. The substitution of lead with copper provides an opportunity in making lead-free perovskite solar cells in the near future.
Graphical abstract
中文翻译：
掺铜铯溴化铅胶体纳米片
我们已经使用配体辅助再沉淀 (LARP) 技术在室内环境中生长了 Cu 掺杂的溴化铯铅 (CsPbBr 3 ) 钙钛矿的胶体纳米片。使用选区衍射和透射电子显微镜，纳米晶体的结构被确定为正交晶相。从未掺杂的 CsPbBr 3纳米晶体的绿色发射 (520 nm) ，我们能够将 1% 掺杂的 CsPbBr 3纳米片的发射转变为蓝色 (464 nm) 。随着掺杂浓度的增加，纳米片的边缘长度增加并导致斯托克斯位移减小。对于未掺杂的 CsPbBr 3，发现光学带隙从 2.6 eV 增加2% 掺杂的样品为 2.81 eV。我们报告说，结合能在 70-110 meV 范围内的激子的形成是蓝色光致发光的原因。已确定绿色发射是由于位于导带边缘以下 210-380 meV 的缺陷水平。PLE 峰没有随着激发波长的增加而变化，表明量子限制效应。在不久的将来，用铜替代铅为制造无铅钙钛矿太阳能电池提供了机会。
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