Heger Julian E, Chen Wei, Zhong Huaying, Xiao Tianxiao, Harder Constantin, Apfelbeck Fabian A C, Weinzierl Alexander F, Boldt Regine, Schraa Lucas, Euchler Eric, Sambale Anna K, Schneider Konrad, Schwartzkopf Matthias, Roth Stephan V, Müller-Buschbaum P
Technical University of Munich, TUM School of Natural Sciences, Department of Physics, Chair for Functional Materials, James-Franck-Str. 1, 85748 Garching, Germany.
College of Engineering Physics, Shenzhen Technology University (SZTU), Lantian Road 3002, Pingshan, 518118 Shenzhen, China.
Nanoscale Horiz. 2023 Feb 27;8(3):383-395. doi: 10.1039/d2nh00548d.
The superlattice in a quantum dot (QD) film on a flexible substrate deformed by uniaxial strain shows a phase transition in unit cell symmetry. With increasing uniaxial strain, the QD superlattice unit cell changes from tetragonal to cubic to tetragonal phase as measured with grazing-incidence small-angle X-ray scattering (GISAXS). The respective changes in the optoelectronic coupling are probed with photoluminescence (PL) measurements. The PL emission intensity follows the phase transition due to the resulting changing inter-dot distances. The changes in PL intensity accompany a redshift in the emission spectrum, which agrees with the Förster resonance energy transfer (FRET) theory. The results are essential for a fundamental understanding of the impact of strain on the performance of flexible devices based on QD films, such as wearable electronics and next-generation solar cells on flexible substrates.
在柔性衬底上受单轴应变作用而变形的量子点（QD）薄膜中的超晶格，在晶胞对称性上呈现出相变。随着单轴应变增加，通过掠入射小角X射线散射（GISAXS）测量可知，量子点超晶格的晶胞从四方相转变为立方相再变回四方相。通过光致发光（PL）测量来探测光电耦合的相应变化。由于量子点间距离的改变，光致发光发射强度随相变而变化。光致发光强度的变化伴随着发射光谱的红移，这与福斯特共振能量转移（FRET）理论相符。这些结果对于从根本上理解应变对基于量子点薄膜的柔性器件（如可穿戴电子产品和柔性衬底上的下一代太阳能电池）性能的影响至关重要。
