The Influence Of Photoelectric Performance Of Perovskite Solar Cells By Potassium Halide Doping

In the field of new photovoltaic power generation,the photoelectric conversion efficiency of perovskite photovoltaic devices with easy preparation and excellent performance has jumped from 3.8%to 25.4%during the development of more than ten years.The key of high efficiency photovoltaic devices is to obtain high quality perovskite films.And the application of additives can obtain high quality perovskite films,such as the doping of alkali metal salt.In particular,potassium salt(K)has a significant effect on improving the morphology of perovskite films,enhancing crystallinity,reducing hysteresis,inhibiting phase separation and non-radiation recombination.However,there are some unclear questions about the doping of alkali potassium salts.Firstly,now the research of potassium ions doping is KI.There are few reports on the additives doping of KBr and KCl,which have similar structure with KI.And some researchers reported that KCl between the electron transport layer and the perovskite film plays a significant role on the effect of defect passivation of perovskite photovoltaic devices.Secondly,the doping mechanism of KI simply summed up the effect of K~+,ignoring the effect of halogen anion in perovskite device,which caused some varied controversial conclusions,such as the position of K~+in perovskite lattice.In the end,it impeded the exploration of deep mechanism of alkali metal K~+doping.To solve the above problems,the effects of the addition of KCl on the performance of perovskite films and devices were investigated from the perspective of carrier dynamics and electrochemical performance.Furthermore,by adding the same molar amount of KI,KBr and KCl into the perovskite precursor,the mechanism of alkali metal potassium halogen doping on the perovskite film and device was systematically explored.The main research contents of the article are as follows:(1)By adding KCl into the perovskite precursor,the effects of the addition of KCl on the surface morphology,crystal orientation,light absorption intensity,photoluminescence and fluorescence carrier life,defect state density,interface transport and photoelectric properties of the perovskite film were revealed,and the photoelectric conversion efficiency of the perovskite solar cells with KCl has been up to more than19%.(2)By introducing the same amount of KI,KBr and KCl to perovskite precursor,it has investigated the influence of alkali potassium halogen doping on perovskite lattice.As a result,it has solved the controversial issues of unclear position of alkali metal potassium ions in the perovskite lattice.Finally,exploring the halogen potassium as additives on the crystallization quality,morphology of perovskite and the important influence of the electro-optical properties,it has analyzed the alkali metal potassium ions in the form of perovskite,illuminated the passivation effect of alkali metals potassium on perovskite films,achieved the photoelectric conversion efficiency of more than 21%.In the article,the mechanism of alkali potassium salt on perovskite thin films and perovskite devices has been systematically investigated,and the controversial issue of the unclear position of alkali potassium ions in the perovskite lattice has been solved.Finally,a method of realizing high efficiency of perovskite devices has been provided by passivation of potassium rich phase.