The Effect Of Hole Transport Layer On The Photoelectric Performance And Stability Of Perovskite Devices

In recent years,perovskite solar cells(PSCs)with high absorption coefficient,excellent carrier transport performance,simple fabrication process,and low cost have attracted tremendous attention in the photovoltaic field.In the past few years,the power conversion efficiency(PCE)of PSCs has improved from 3.8%to more than 22%,with the rapid development which has never appeared before in the photovoltaic field.However,with the progressively mature technology of PSCs,the internal problems are gradually exposed.The stability problem of PSCs is a major obstacle to the further development of its commercialization.Most studies have attributed the poor stability of perovskite devices to perovskite material,which is easy to decompose.However,the PSC is composed of multilayer structures.The photoelectric properties of any layer would affect the performance and stability of the whole device.Some studies have shown that the charge transport layers of PSCs would affect the charge transport performance of the whole device,and it would also have an important effect on the stability of the device.In this paper,several hole transport materials(HTMs)are fabricated,and the effect of these materials on the photoelectric properties and stability of PSCs are studied systematically.In the beginning,the basic knowledge of PSCs and the main research status in this field are introduced.In view of the traditional hole transport material(HTM)spiro-OMeTAD,the effect of different doped spiro-OMeTAD materials on photoelectric properties and stability of perovskite devices and its intrinsic mechanism are systematically studied.The results show that the Li/FK209-doped devices exhibit excellent photoelectric properties without exposure to air,thus effectively avoiding the erosion of perovskites by air.Further research shows that the introduction of Li and FK209 can not only improve the conductivity of spiro-OMeTAD,but also tune the work function of the material,which promotes the charge transport in devices effectively.Based on the study of the commonly used hole transport material spiro-OMeTAD,it is proposed that copper-based compounds(mainly Cu2S)could be used as new hole transport layers.In the experiment,Cu2S thin films are prepared by vacuum evaporation and spin coating method,respectively.The PCE of devices gained in research is 8%with an open-circuit voltage 624.93mV,a short-circuit current 23.16mA/cm2,a fill factor 55.25%,and the current density-voltage(J-V)curves of devices have obvious hysteresis.Based on the experimental results,we believe that the rough surface morphology and near metal properties of Cu2S films,and the interaction between perovskite/Cu2S/Au are the main reasons for the poor performance of the devices.Considering the diffusion of metal ions from charge transport layers to the perovskite absorber,the effect of copper ion doping on the photoelectric properties and stability of perovskite films and devices is studied.Results show that doping with low molar concentration of copper ions can significantly reduce the phase transition temperature of perovskite films(FAPbI3),increase the absorbance of films,and improve the crystallization and stability of films.The stability of devices is also improved,significantly.The best stability of devices is gained with CuI-0.1 mol%doped perovskite absorber.After 170 hours of continuous testing under light,the PCE decrease of the device is less than 2%.However,when the doping concentration of copper ions is high,the performance of perovskite films and perovskite devices are significantly reduced.In this paper,the method of studying the effect of HTMs on the photoelectric properties and stability of PSCs has been proposed.It is hoped that the corresponding research methods and conclusions will serve as a reference for the following research.