Luo Tianhong, Zhang Ganghua, Wen Jinrong, Liu Zhanqiang, Hou Jingshan, Li Dezeng, Fang Yongzheng
School of Materials Science and Engineering, Shanghai Institute of Technology, Shanghai 201418, P. R. China.
Department of Materials Chemistry, Huzhou University, 759 East Erhuan Road, Huzhou 313000, P. R. China.
Inorg Chem. 2024 Sep 30;63(39):18296-18303. doi: 10.1021/acs.inorgchem.4c03163. Epub 2024 Sep 19.
Lead-free molecular ferroelectrics have garnered considerable attention for their promising potential, but such species with narrow band gap and sensitive photoelectric response are yet inadequate. Herein, we demonstrated the bulk ferroelectric photovoltaic effect in a novel lead-free molecular ferroelectric [CNH][BiI] with a Curie temperature () of 366 K and a narrow band gap () of 1.92 eV. The transformation of the crystal structure from the polar space group 2 to the nonpolar space group 2/ was elucidated using single-crystal X-ray diffraction. Room-temperature (RT) hysteresis loop reveals the intrinsic ferroelectricity of [CNH][BiI] with a relative small coercive field ( ∼ 0.27 kV/cm), saturation polarization ( ∼ 1.87 μC/cm), and remanent polarization ( ∼ 1.61 μC/cm). [CNH][BiI]-based solar device exhibits significant PV effects with a steady-state photocurrent () of 3.54 μA/cm and a photovoltage () of 0.34 V under AM 1.5 G illumination, which can be significantly improved by adjusting the ferroelectric polarization, reaching a maximum of 140 μA/cm and of 0.51 V. This work offers a promising avenue for lead-free molecular ferroelectric materials in the field of optoelectronic devices.
无铅分子铁电体因其潜在的应用前景而备受关注，但这类带隙窄且光电响应敏感的材料仍存在不足。在此，我们展示了一种新型无铅分子铁电体[CNH][BiI]中的体铁电光伏效应，其居里温度（）为366 K，带隙窄（）为1.92 eV。利用单晶X射线衍射阐明了晶体结构从极性空间群2到非极性空间群2/的转变。室温（RT）磁滞回线揭示了[CNH][BiI]的本征铁电性，其矫顽场相对较小（约0.27 kV/cm），饱和极化强度（约1.87 μC/cm），剩余极化强度（约1.61 μC/cm）。基于[CNH][BiI]的太阳能器件在AM 1.5 G光照下表现出显著的光伏效应，稳态光电流（）为3.54 μA/cm，光电压（）为0.34 V，通过调节铁电极化可显著提高，最大可达140 μA/cm和0.51 V。这项工作为无铅分子铁电材料在光电器件领域提供了一条有前景的途径。
