Piezoelectric And Ferroelectric Photovoltaic Properties Of Orthogonal Fe Doped KTN Crystals

With the rapid development of economy,people begin to face the increasingly serious problems of environmental pollution and energy shortage.The development and utilization of renewable clean energy such as solar energy,water energy and wind energy has become an effective solution to the problem,among which solar photovoltaic cells have always been the focus of research.Since 1839,Becquerel,a French scientist,discovered the photovoltaic effect,a lot of research has been put into the photovoltaic field,and now the photovoltaic devices with p-n junction semiconductor material as the core have been applied.However,the traditional p-n junction semiconductor materials are limited by the intrinsic energy gap of the materials,and the photoelectric conversion efficiency is limited.Later,it was found that the photovoltaic effect in ferroelectrics,compared with the traditional photovoltaic effect,has the characteristics of much larger open circuit voltage than the material band gap width and can quickly separate the photogenerated carriers.And ferroelectric materials can regulate their photovoltaic performance through internal polarization state,so ferroelectric photovoltaic materials are considered as one of the most likely candidates to replace p-n junction semiconductor photovoltaic materials.Doping transition metal ions in ferroelectrics by acceptor doping can effectively reduce the band gap of ferroelectric photovoltaic materials,and affect the ferroelectric,piezoelectric and photovoltaic properties of materials.In different crystal phases,orthorhombic phase crystals often have the characteristics of large piezoelectric properties.In this paper,the phase structure of orthorhombic Fe-KTN crystal is verified by using quasi-static piezoelectric coefficient meter and strain curve to characterize the giant piezoelectric coefficient of orthorhombic Fe-KTN crystal after polarization,and the source of the giant piezoelectric coefficient is explored by combining polarizing microscope and PFM.The acceptor doping transition metal elements are discussed The influence of cross phase Fe-KTN crystal is analyzed by using the constraint mechanism of defect dipole,and the dynamic inversion process of the ferroelectric domain in the cross phase Fe-KTN crystal is quantitatively and intuitively demonstrated by the evolution process of the double hysteresis in different external electric fields,A sandwich type ferroelectric photovoltaic device was constructed and a photovoltaic test system was set up to characterize the photovoltaic performance of the orthogonal phase Fe-KTN crystal.The differences of the photovoltaic performance of the orthogonal phase Fe-KTN crystal under different polarization states were explored.The differences were explained by the polarization principle of the crystal and the Schottky barrier caused by the contact between the electrode and the crystal.