Towards a Spectrally Customized Photoresponse from an Organic-Inorganic Hybrid Ferroelectric.

Photosensitive organic-inorganic hybrid ferroelectrics are emerging as a new class of promising materials with a broad spectral response (e.g., visible light, UV light, and IR light) for optoelectronic applications. However, spectrally customized photoresponses in ferroelectrics have not been achieved. Herein, we report a photosensitive organic-inorganic hybrid ferroelectric, (diisobutylammonium)3 ClCoCl4 (1), with a notable spontaneous polarization of approximately 4.6 μC cm-2 and high Curie temperature (Tc =372.5 K). More interestingly, it features spectrally selective absorption at specific wave bands ranging from 550 to 700 nm with a large absorption coefficient, which was assigned to the d-d transition of Co2+ from the 4 A2 to the 4 T1 (P) state. It is emphasized that 1 shows spectrally customized photosensitivity with distinct photocurrent generation under light illumination at 550-700 nm. This is the first hybrid photosensitive ferroelectric with a spectrally customized photoresponse. This finding should lead to innovative applications of hybrid photosensitive ferroelectrics, especially towards spectrally selective optoelectronic devices.