Chuang Ching-An, Lin Min-Han, Yeh Bo-Xian, Ho Ching-Hwa
Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology Taipei 106 Taiwan
Graduate Institute of Electro-Optical Engineering, Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology Taipei 106 Taiwan.
RSC Adv. 2018 Jan 12;8(5):2733-2739. doi: 10.1039/c7ra11600d. eCollection 2018 Jan 9.
Flexible optoelectronics devices play an important role for technological applications of 2D materials because of their bendable, flexible and extended two-dimensional surfaces. In this work, light emission properties of layered gallium selenide (GaSe) crystals with different curvatures have been investigated using bending photoluminescence (BPL) experiments in the curvature range between = 0.00 m (flat condition) and = 30.28 m. A bendable and rotated sample holder was designed to control the curvature (strain) of the layered sample under upward bending uniformly. The curvature-dependent BPL results clearly show that both bandgaps and BPL intensities of the GaSe are curvature dependent with respect to the bending-radius change. The main emission peak (bandgap) is 2.005 eV for flat GaSe, and is 1.986 eV for the bending GaSe with a curvature of 30.28 m (the maximum bending conditions in this experiment). An obvious redshift ( energy reduction) for the GaSe BPL peak was detected owing to the c-plane lattice expansion by upward bending. The intensities of the corresponding BPL peaks also show an increase with increasing curvature. The correlations between BPL peak intensity, shiny area and bond-angle widening of the bent GaSe under laser excitation have been discussed. The lattice constant emission energies of the bending GaSe was also analyzed. An estimated lattice constant bandgap relation was present for further application of the layered GaSe in bendable flexible light-emission devices.
柔性光电器件因其可弯曲、灵活且具有扩展的二维表面，在二维材料的技术应用中发挥着重要作用。在这项工作中，通过弯曲光致发光（BPL）实验，研究了曲率在(r = 0.00 m)（平面状态）至(r = 30.28 m)范围内、具有不同曲率的层状硒化镓（GaSe）晶体的发光特性。设计了一个可弯曲且能旋转的样品架，以均匀控制层状样品向上弯曲时的曲率（应变）。曲率相关的BPL结果清楚地表明，GaSe的带隙和BPL强度均随弯曲半径的变化而与曲率相关。对于平面GaSe，主要发射峰（带隙）为2.005 eV，而对于曲率为30.28 m（本实验中的最大弯曲条件）的弯曲GaSe，该值为1.986 eV。由于向上弯曲导致c面晶格膨胀，检测到GaSe的BPL峰出现明显的红移（能量降低）。相应BPL峰的强度也随曲率增加而增大。讨论了激光激发下弯曲GaSe的BPL峰强度、发光面积与键角加宽之间的相关性。还分析了弯曲GaSe的晶格常数与发射能量。提出了估计的晶格常数与带隙关系，以供层状GaSe在可弯曲柔性发光器件中的进一步应用。
