Lei Lei, Seyitliyev Dovletgeldi, Stuard Samuel, Mendes Juliana, Dong Qi, Fu Xiangyu, Chen Yi-An, He Siliang, Yi Xueping, Zhu Liping, Chang Chih-Hao, Ade Harald, Gundogdu Kenan, So Franky
Department of Materials Science and Engineering, Organic and Carbon Electronics Lab (ORaCEL), North Carolina State University, Raleigh, NC, 27695, USA.
Department of Physics, Organic and Carbon Electronics Lab (ORaCEL), North Carolina State University, Raleigh, NC, 27695, USA.
Adv Mater. 2020 Apr;32(16):e1906571. doi: 10.1002/adma.201906571. Epub 2020 Feb 28.
Quasi-2D Ruddlesden-Popper halide perovskites with a large exciton binding energy, self-assembled quantum wells, and high quantum yield draw attention for optoelectronic device applications. Thin films of these quasi-2D perovskites consist of a mixture of domains having different dimensionality, allowing energy funneling from lower-dimensional nanosheets (high-bandgap domains) to 3D nanocrystals (low-bandgap domains). High-quality quasi-2D perovskite (PEA) (FA) Pb Br films are fabricated by solution engineering. Grazing-incidence wide-angle X-ray scattering measurements are conducted to study the crystal orientation, and transient absorption spectroscopy measurements are conducted to study the charge-carrier dynamics. These data show that highly oriented 2D crystal films have a faster energy transfer from the high-bandgap domains to the low-bandgap domains (<0.5 ps) compared to the randomly oriented films. High-performance light-emitting diodes can be realized with these highly oriented 2D films. Finally, amplified spontaneous emission with a low threshold 4.16 µJ cm is achieved and distributed feedback lasers are also demonstrated. These results show that it is important to control the morphology of the quasi-2D films to achieve efficient energy transfer, which is a critical requirement for light-emitting devices.
具有大激子结合能、自组装量子阱和高量子产率的准二维Ruddlesden-Popper卤化物钙钛矿在光电器件应用中引起了关注。这些准二维钙钛矿的薄膜由具有不同维度的畴的混合物组成，允许能量从低维纳米片（高带隙畴）向三维纳米晶体（低带隙畴）进行漏斗状传输。通过溶液工程制备了高质量的准二维钙钛矿(PEA)(FA)PbBr薄膜。进行掠入射广角X射线散射测量以研究晶体取向，并进行瞬态吸收光谱测量以研究电荷载流子动力学。这些数据表明，与随机取向的薄膜相比，高度取向的二维晶体薄膜具有更快的从高带隙畴到低带隙畴的能量转移(<0.5 ps)。使用这些高度取向的二维薄膜可以实现高性能发光二极管。最后，实现了阈值低至4.16 μJ cm的放大自发发射，并展示了分布反馈激光器。这些结果表明，控制准二维薄膜的形态对于实现高效能量转移很重要，这是发光器件的关键要求。
