Research On Efficient Perovskite Solar Cells With Novel Hole-transport Material

Perovskite solar cell(PSC)develops rapidly in the last 10 years,and efficiency is approaching the theoretical limitation.However,the environmental stability problem of the battery still exists,which largely contributes to hole-transport materials(HTMs).In order to conquer the challenges of low stability and high cost in HTMs,this paper replaces traditional polytriphenylamine(PTAA)with two cheap and easily accessible organic small-molecule HTMs.In order to prepare high-efficiency solar cells based on new HTMs,the classical planar inverted PSC is studied at first and the device parameters are optimized.PTAA is served as HTM,and the device structure is: transparent conductive electrode ITO/ hole transport layer PTAA/perovskite/electron transport layer PC61BM/acetylacetone zirconium/silver.By optimizing devices,including concentration of PTAA,the composition of perovskite and addition of buffer layer,we achieve 19.1% efficiency.This paper reports two cheap new HTMs and their application in PSCs is studied.The properties of the two materials were tested at first,including solubility,wettability,thermal stability and electrochemical properties.The difference between the two molecular structures and properties was explored.We find that their energy level match the perovskite layer very well.Through the analysis of devices and perovskite film,we get the reasons for their different efficiency,which mainly influenced by the defect concentration at the hole transport layer and perovskite interface.The results show that the new HTMs can guarantee better interface contact with perovskite,resulting lower concentration of interface defect.The two materials were applied to planar inverse PSC.By optimizing the annealing temperature of the hole-transporting materials,we obtained device with efficiency of up to 18.4%,which was close to the device data that contain classical PTAA structures under the same experimental conditions.This research indicates these two new HTMs have the potential to replace PTAA commercially,and provides a theoretical basis for the molecular design of HTM for PSCs.