Polarization Field Tunes Photoelectric Properties Of Organic-inorganic Hybrid Perovskites Devices

In recent years,with the continuous development of organic-inorganic hybrid perovskite materials,it has become a research hot topic of photovoltaic and optoelectronic devices.Organic-inorganic hybrid perovskite materials have excellent optical and electrical properties,such as high carrier mobility,tunable spectral absorption range,long diffusion length,and simple and economical preparation.It has become a research hotspot in photovoltaic devices,such as light emitting diodes(LEDs),photodetectors and other device,and has great application potential.In 2009,the conversion efficiency of organic-inorganic hybrid perovskite solar cells was 3.8%,which has exceeded 25.5%so far.Based on piezoelectric polymer and organic-inorganic perovskite composite solar cell device coupling photoelectric properties and piezoelectric properties,can show higher open circuit voltage than band gap.In addition,the photodetector based on organic-inorganic hybrid perovskite structure polycrystalline material has a wavelength detection range from 300 nm to 1000 nm,and has the advantages of high response and sensitivity.At present,the research focuses on the basic structure,working mechanism,interface optimization,preparation process and other aspects to improve the photovoltaic and photoelectric properties of organic-inorganic hybrid perovskite structure materials.Piezo-phototronic devices have the characteristics of force-optical-electric coupling,which can control the polarization between devices and interface by external electric field and strain,tune the separation,recombination and transport of carriers in junction area or interface,and control the schottky barrier height of metal-semiconductor contact.The polarization generated by external electric field or strain can change the built-in electric field of the device,regulate the interface barrier height,and provide an effective method to improve the carrier generation and injection efficiency of perovskite devices and improve the performance of photovoltaic and optoelectronic devices.In this dissertation,the polarization charge and polarization field are experimentally studied to improve the performance of photovoltaic and optoelectronic devices based on organic-inorganic hybrid perovskite.The efficiency of solar cells was improved in organic-inorganic hybrid perovskite devices by external electric field polarization.By tuning the polarization field generated by strain on the interface,the optical response of the photodetector is improved and the response time or the photodetector is reduced.1.Polarization field enhances the performance of solar cells based on organic-inorganic hybrid perovskite structure materials.In this study,it is found that the polarization field can improve the power conversion efficiency(PCE),introduce polarization in the perovskite structure absorption layer,and improve the built-in electric field and reduce the interface barrier,which can greatly improve the carrier separation and injection,thereby enhancing the photovoltaic performance.Perovskite/polymer(P(VDF-TrFE))composite thin film solar cells were prepared by doping piezoelectric polymer polyvinylidene fluoride-cotrifluoroethylene(P(VDF-TrFE))into perovskite.The experimental results show that the composite film device can improve the performance of perovskite solar cells by external electric field polarization.This method is simple and effective.The conversion efficiency of solar cells increases from 18.3%to 22.1%,the short circuit current density(J_sc)increases from 21.9 mA·cm^-2 to 24.2 mA·cm^-2,and the open circuit voltage(V_oc)increases from 1.14 V to 1.18 V.2.The external electric field tunes the polarization properties of piezoelectric polymer and organic-inorganic hybrid perovskite thin films,and the photovoltaic properties of solar cells based on piezoelectric polymer and organic-inorganic hybrid perovskite composite films.The piezoelectric polymer and organic-inorganic hybrid perovskite composite films were prepared,and the piezoelectric polymer and organic-inorganic hybrid perovskite composite films were polarized by an external electric field.By KPFM and other characterization methods,the polarization field can regulate the photovoltaic properties of piezoelectric polymer and organic-inorganic hybrid perovskite composite thin film solar cells by regulating the polarization properties of piezoelectric polymer and organic-inorganic hybrid perovskite composite film.3.Strain-induced polarization field enhances the performance of organic-inorganic hybrid perovskite photodetectors.A novel piezo-phototronic photodetector based on MAPbI₃ polycrystalline perovskite was designed and prepared.The regulation mechanism of the polarization field generated by strain on the photovoltaic and photodetector properties of polycrystalline perovskite materials was studied.Strain can increase the photocurrent by 2.6 times and reduce the response time of the device by about38%.Based on the metal-semiconductor contact model,the strain indduced polarization field can not only promote the generation,separation and transportation of carriers in organic-inorganic hybrid perovskite structure materials devices through strong local electric field,but also affect the energy band of devices by adjusting the barrier height of metal-semiconductor contact,and improve the performance of photodetectors.