Noncentrosymmetric Columnar Liquid Crystals with the Bulk Photovoltaic Effect for Organic Photodetectors

The bulk photovoltaic effect (BPVE) has drawn intensive attention due to its unique features that cannot be accessed with the conventional photovoltaic effect. However, the BPVE is observed in noncentrosymmetric materials and has been studied mainly for inorganic materials. Here, we report a simple subphthalocyanine (SubPc) derivative that assembles into a noncentrosymmetric columnar liquid crystal with the help of a DC E-field. These columnar assemblies exhibit the BPVE over a wide range of wavelengths up to 650 nm. Furthermore, just by sandwiching this columnar assembly between two ITO electrodes, the resultant device reaches a light-on/off ratio, I_light/I_dark, as high as 6.6 × 10³, indicating that the polar columnar assemblies with SubPcs are promising for photodetectors.