Current-voltage Hysteresis In Mesoscopic Perovskite Solar Cell

Perovskite Solar Cells(PSCs)have developed rapidly,and their certified photoelectric conversion efficiency has reached to 22.1%,which indicates a wide range of application prospects.Though the efficiency of perovskite solar cells is increasing rapidly,it still has some theoretical problems need to be solved.It is well known that during the solar cell performance test process,the current-voltage curves(I-V curves)show significant differences with different scanning directions,which is called perovskite solar cell hysteresis effect phenomenon.The hysteresis effect is also related to the scanning speed,starting bias,device structure,light intensity,etc..The main contents of this thesis which about hysteresis include three parts as follows:Firstly,based on printable hole-conductor free mesoscopic perovskite solar cells,the invertedhysteresis perovskite solar cell devices were observed.Through a series of condition control and process optimization,three kinds of devices,named as normal-hysteresis,hysteresis-free and inverted-hysteresis devices are prepared.Secondly,the J-V curves of the three types of hysteretic effect devices and the device parameter data under different scan rates were tested.Hysteresis index is introduced and some regularities are found by statistical analysis.Thirdly,the samples with different thicknesses of TiO2 compact layer and UVO treatment time were fabricated.A series of tests like PL and Hall effect etc.were used to compare the differences between the three types of devices.Three different cases of the equivalent circuit diagram model were built based on the cyclic voltammetry measurement in dark and the recombination resistance under AM 1.5 simulated light.Such tunable hysteresis phenomenon for PSCs provides important insights towards the understanding of this rapidly developing photovoltaic technology and the further improvement in device performance.