Jiang Xingxing, Xu Zhengwei, Zheng Yueshao, Zeng Jiang, Chen Ke-Qiu, Feng Yexin
Hunan Provincial Key Laboratory of Low-Dimensional Structural Physics & Devices, School of Physics and Electronics, Hunan University, Changsha 410082, China.
Phys Chem Chem Phys. 2022 Jul 21;24(28):17323-17328. doi: 10.1039/d2cp01315k.
Revealing the origin of self-trapped excitons is a prerequisite for further improving the photoluminescence efficiency of low-dimensional organic perovskites. Here, the microscopic formation mechanism of intrinsic self-trapped excitons in one-dimensional (1D) CNHPbX (X = Cl, Br and I) systems is investigated, and the polarization-luminescence relationship is established. Our results show that 1D-CNHPbX has a low electronic dimension (flat band characteristics), which facilitates the formation of intrinsic self-trapped excitons. The potential well formed by local distortion of the [PbX] octahedron is the origin of exciton self-trapping. Combined with the electronic density of states and partial charge density, we further confirmed the existence of intrinsic self-trapping excitons in 1D-CNHPbX. In addition, we found that the breaking of the central inversion symmetry will induce electric polarization, which greatly improves the transition probability of electrons. These results could potentially offer a new direction for improving the luminescence properties of 1D organic lead halide perovskites.
揭示自陷激子的起源是进一步提高低维有机钙钛矿光致发光效率的前提条件。在此，研究了一维（1D）CNHPbX（X = Cl、Br和I）体系中本征自陷激子的微观形成机制，并建立了偏振发光关系。我们的结果表明，1D-CNHPbX具有低电子维度（平带特性），这有利于本征自陷激子的形成。由[PbX]八面体的局部畸变形成的势阱是激子自陷的起源。结合态密度和部分电荷密度，我们进一步证实了1D-CNHPbX中本征自陷激子的存在。此外，我们发现中心反演对称性的破坏会诱导电极化，这大大提高了电子的跃迁概率。这些结果可能为改善一维有机卤化铅钙钛矿的发光性能提供一个新方向。
