Details

Autor(en) / Beteiligte

• Guo, Zhu
• Han, Dingchong
• Liu, Huan
• Hu, Yaoqiao
• Zhang, Weixiong
• Chen, Rui
• Mao, Lingling

Titel

Controlling the Orientation‐Dependent Second Harmonic Generation in Hybrid Germanium Perovskites

Ist Teil von

• Angewandte Chemie, 2024-08, Vol.136 (32), p.n/a

Ort / Verlag

Weinheim: Wiley Subscription Services, Inc

Erscheinungsjahr

2024

Quelle

Wiley Online Library All Journals

Beschreibungen/Notizen

• Manipulating the crystal orientation plays a crucial role in the conversion efficiency during second harmonic generation (SHG). Here, we provide a new strategy in controlling the surface‐dependent anisotropic SHG with the precise design of (101) and (2 1‾ ${\bar 1}$ 0) MAGeI3 facets. Based on the SHG measurement, the (101) MAGeI3 single crystal exhibits larger SHG (1.3×(2 1‾ ${\bar 1}$ 0) MAGeI3). Kelvin probe force microscopy imaging shows a smaller work function for the (101) MAGeI3 compared with the (2 1‾ ${\bar 1}$ 0), which indirectly demonstrates the stronger intrinsic polarization on the (101) surface. X‐ray photoelectron spectroscopy confirms the band bending within the (101) facet. Temperature‐dependent steady‐state and time‐resolved photoluminescence spectroscopy show shorter lifetime and wider emission band in the (101) MAGeI3 single crystal, revealing the higher defect states. Additionally, powder X‐ray diffraction patterns show the (101) MAGeI3 possesses larger in‐plane polar units [GeI3]− density, which could directly enhance the spontaneous polarization in the (101) facet. Density functional theory (DFT) calculation further demonstrates the higher intrinsic polarization in the (101) facet compared with the (2 1‾ ${\bar 1}$ 0) facet, and the larger built‐in electric field in the (101) facet facilitates surface vacancy defect accumulation. Our work provides a new angle in tuning and optimizing hybrid perovskite‐based nonlinear optical materials. Facet engineering is an effective approach to enhance second harmonic generation (SHG) efficiency. Here, we demonstrate the larger polarization from the higher in‐plane polar units [GeI3]− density within the (101) MAGeI3, results in the stronger SHG in the (101)‐oriented than the (210)‐oriented methylammonium germanium iodide crystals.