Structural Design And Performance Research Of Ferroelectric Photovoltaic Devices

As a new energy product,solar cells are gradually being widely used.The main way of solar energy conversion is through photovoltaic conversion of solar cells.Photovoltaic effects usually involve two basic processes:one is the generation of electron-hole pairs,and the other is the separation of electron-hole pairs.For the photovoltaic effect of a semiconductor,the electric field at the space charge region of the P-N junction or Schottky barrier acts in separating the charge carriers.In recent years,the research results show that ferroelectric materials have great application prospects in new solar cells,photodetectors and optoelectronic memories,mainly due to their spontaneous polarization and the ability to reverse the external electric field and open circuit voltage.Far more unique than optical band gaps.However,since most of the ferroelectric materials have a wide band gap and a low electrical conductivity.The photocurrent of ferroelectric thin film devices is currently on the order ofμA/cm~2.Among various ferroelectric thin films,lead zirconate titanate(PZT)and lead zirconate titanate(PLZT)films are most popular due to their excellent ferroelectric properties.However,the main disadvantage of PZT and PLZT is that it contains lead.Therefore,it is now necessary to pay attention to one of the lead-free ferroelectric materials.Barium titanate(BTO)is the most common perovskite ferroelectric material and can be used as a capacitor,ferroelectric memory,etc.due to its excellent dielectric,piezoelectric and ferroelectric properties.Based on this background,the microstructure and ferroelectric properties of Ca-doped and Zr-doped BTO films and the optical properties of the films were investigated.In this paper,the sol-gel method is used to analyze the structural,optical and electrical properties of the films produced by different annealing processes to find the best annealing process:when the annealing temperature is 700°C,the annealing time is 480s and the annealing layer When the number is 4 layers,the film has the best ferroelectric and optical properties.Based on the optimal annealing process,BCZT polycrystalline films doped with different Ba/Ca ratios and different Ti/Zr ratios were investigated.The ferroelectric analyzer showed that when the Ca content was 0.15,the film had a large residual polarization value,and the optical absorption spectrum of the film was measured by an ultraviolet-visible spectrophotometer and fitted by the(α?ν)~2~?νcurve relationship.It is found that the band gap is about 3.07eV.BCZT films with different Zr doping ratios were prepared on the basis of optimal Ca doping.When the Zr content is 0.2,the film has a large residual polarization value.With the increase of Zr doping amount,the film is optical.The band gap also increases.Through analysis and comparison,the best Ca,Zr ratio film is obtained.Ferroelectric photovoltaic devices with different electrodes were prepared by ion sputtering method,and the mechanism of their photovoltaic performance was analyzed.It is concluded that sputtering the Au electrode is beneficial to improve the photovoltaic properties of the film.