Synthesis Of Fulleropyrrolidine Derivatives And Their Applications In Polymer/Perovskite Solar Cells

With the rapid development of science and technology and the continuous improvement of the industrialization,the consumption of traditional fossil energy is increasing,which directly leads to energy shortages and serious environmental problems.So it is urgent to develop new renewable energy sources.Solar energy has attracted people’s attention because of its advantages of universality,cleanness and permanency.Polymer solar cells and perovskite solar cells have been regarded as two promising photovoltaic technologies due to their merits,such as low cost,simple processing,lightweight and the possibility to be fabricated on flexible substrates.Currently,the soluble fullerene derivatives,including[6,6]-phenyl-C61-butyric acid methyl ester(PC61BM)and its corresponding C70 derivative PC71BM,have became the dominant acceptors/electron transport layers in high performence polymer/perovskite solar cells.Nevertheless,PC61BM and PC71BM suffer from some intrinsic drawbacks such as relatively low lowest unoccupied molecular orbital(LUMO)and weak visible absorption.Therefore,developing novel materials is highly desirable,which can not only overcome the above-mentioned issues,but also mimic the superior electron transporting behaviour of fullerene.In this thesis,a series of fulleropyrrolidine derivatives were synthesized via Prato reaction and applied as acceptors/electron transport materials in polymer/perovskite solar cells.’The optical,electrochemical and photovoltaic properties of these fullerene derivatives were also evaluated.A class of alkoxy substituted N-phenyl-[60]fulleropyrrolidine derivatives were synthesized(FP1-FP5),UV-vis absorption measurements showed that FP1-FP5 all have stronger absorbtion than PC61BM in the range between 400 and 490 nm.Cyclic voltammetry results showed that the LUMO energe levels of FP1-FP5 are similar to that of PC61BM.The photovaltic performance of the polymer solar cells based on a blend of fulleropyrrolidine with poly(3-hexylthiophene)(P3HT)was investigated.As a result,the P3HT:FP2 device exhibited the highest power conversion efficiency(PCE)of 3.27%and the P3HT:FP3 device showed the best PCE of 3.30%,which were similar to that of P3HT:PC61BM.This indicates that the specific position of the methoxy substitution has a significant effect on the photovoltaic performance of fulleropyrrolidine derivative.In addition,we also explored the photovoltaic performence of polymer solar cells based on FP2 and FP3 blended with narrow bandgap polymer PTB7.A series of N-phenyl-[60]fulleropyrrolidine electron transport materials were synthesized(FP6-FP9).UV-vis absorption spectra of these derivatives showed that all of them have stronger absorbtion than that of PC61BM in the range between 400 and 480 nm.Cyclic voltammetry results showed that their LUMO energy levels are similar to that of PC61BM.The PCEs of perovskite solar cells using FP6/TiO2 and FP7/TiO2 as electron transport layers were 14.82%,12.29%,respectively.Meanwhile,the photovaltic performence of polymer solar cells based on a blend of fulleropyrrolidine with P3HT was also investigated.The P3HT:FP6 device exhibited the highest PCE of 2.67%and the P3HT:FP9 device showed the best PCE of 2.69%.In addition,we also explored the photovoltaic performence of FP6 based on narrow bandgap donor PTB7.The highest PCE of PTB7:FP6 device was 5.63%.Compared to methoxy groups,the thienyl-substituted N-phenyl-[60]fulleropyrrolidine may have better compatibility with narrow bandgap polymers.