Research On Photosensitive Devices Based On 1,6 Hexamethylenediamine Pentaiodobismuth Bismuth Ferroelectric Material

Recently,a new molecular ferroelectric:hexane-1,6-diammonium pentaiodobismuth(HDA-BiI5)was discovered,which adopts a band gap with 1.89 electron volts.HDA-BiI5 bears not only highly applicable ferroelectric properties,but also the ability to absorb most UV-vis region of solar spectrum.Adjusting the ferroelectric polarization would enhance the performance of the(HDA-Bils)-based photodetectors.Compared with traditional inorganic materials,molecular ferroelectrics have merits such as lightweight,environmental friendliness,mechanically flexibility,easy processing,which could be used in photodetector.In this paper,the photodetectors based on HDA-BiI5 were investigated.The crystal structure,elemental composition and energy band structure of the HDA-BiI5 films and the ferroelectric properties of HDA-BiI5 thin films were studied.In order to investigate the effects of the different device structures and ferroelectric polarization on the photoelectric properties of the(HDA-BiI5)-based photodetectors,the conventional and inverted structures of photodetectors were fabricated and polarized for both photodetectors.The main content is as follows:1.HDA-Bils films were prepared on substrates by spin coating method.The crystal structure,elemental composition and energy band structure of the HDA-BiI5 films were investigated.The excellent ferroelectricity was confirmed from HDA-BiI5 thin film form by Piezoresponse Force Microscopy.2.HDA-BiI5 has been utilized as the photosensitive layer for photodetectors.In order to compare the performance of the photodetectors with different structures,conventional and inverted structures of photodetectors were fabricated.The results show that the photodetectors of both structures can produce photoresponse to laser light at 375 nm and 532 nm.In general,the performance of the conventional structure photodetector is better than that of the inverted structure.3.The performance of polarized photodetectors of two structures were tested.The results show that impressive polarization-induced enhancement of photoelectric performance has been achieved in the HDA-BiI5-based photodetectors of two structures.The conventional structured photodetectors exhibited the photocurrent of 588 nA,the dark current of 0.828 nA,the light responsivity of 94.08 ?A/W,the switching ratio of 710 and the specific detectivity of 1.4E9 Jones.The inverted structure photodetector achieving the photocurrent of 60.1 ?A and dark current of 0.0147 ?A and photoresponse of 9616 ?A/W and switching ratio of 4088 and specific detectivity of 3.5E10 Jones.