The Research Of New Hole Transport Materials For Perovskite Solar Cells

In recent years,organic-inorganic lead halide perovskite solar cells(PVSCs)have attracted intensive attention.Their power conversion efficiency(PCE)has rapidly increased from 3.8%to over 22%in past decade.PVSCs have many advantages,including facile synthesis process,ultra-high optical absorption,and superior photovoltaic properties.The architecture of PVSCs consists of two electrodes,an electron transport layer(ETL),perovskite absorber layer,and a hole transport layer(HTL).All of them are indispensable for achieving high-performance perovskite solar cells.Electons tranfer to FTO substrate through ETL,which suppresses holes at same time.Meanwhile,holes transfer to the metal electrode through HTL.Charge transport layers play important roles in the separation of holes and electrons.Therefore,good ETL and HTL materials are essential for achieving high PCE of PVSCs.In this thesis,we systematically investigate the mechanism of the perovskite solar cell,and the method for efficient HTL(e.g.CZ-TA and TRUX-E-T)synthesis.With above mentioned HTLs,we achieve a PCE comparable to spiro-OMeTAD cases.Furthermore,we study the flexible perovskite solar cells and find a new method to improve the performance of SnO2 and therefore,PVSCs.Firstly,a carbazole-based hole-transporting material named CZ-TA and a truxene-based hole-transporting material named TRUX-E-T have been developed through a simple synthesis method,respectively.They both show great solubility in chlorobenzene and toluene.To evaluate their performance,we measure their thermal stability,absorption spectra,photoluminescence spectra and charge transfer at perovskite/hole transport layer interface,which indicates CZ-TA and TRUX-E-T could be promising hole transport material candidates.Morever,the costs of CZ-TA and TRUX-E-T based PVSCs are very low,which shows good PCE of over 18%and fill factor(FF)over 80%unde reverse voltage scan at the same time.Secondly,we systematically study flexible PVSCs.We report a special method to improve the performance of the device with SnO2 as ETL.We use water vapor to treat the SnO2 electron transport layer and find its conductivity and electrical mobility of SnO2 layer are much improved.In summary,the flexible perovskite solar cells show higher open-circuit voltage(Voc)and FF and lower J-V hysteresis.Our best-performing flexible PVSCs shows a PCE of 18.36%and 17.12%under reverse voltage scan and forward voltage scan,respectively.