Functionalization Of(Endohedral)Fullerene Derivatives And Application In Perovskite Solar Cells

The emergence of fullerene has long promoted the development of carbon materials.Tremendous efforts were taken to promote functionalization of fullerene derivatives with different ? systems,which in turn,have yielded a wealth in different fields,such as drug targeted delivery carriers,photovoltaic materials and Supramolecular chemistry,and in recent years,fullerene derivatives have received extensive attention in the field of perovskite solar cells due to their outstanding electron transport capabilities.We have utilized the fullerene cationic intermediates to realize the synthesis a series of corresponded fullerene derivatives which undergoes reaction mechanisms including intramolecular rearrangement reaction,ring formation reaction,and coupling reaction etc.,and the synthesized materials have been successfully applied in Perovskite solar cells.At the same time,as a rare case of fully-characterized endohedral fullerenes,lithium encapsulated fullerene has also been widely studied due to its higher reactivity than its empty analogue.This thesis mainly demonstrates the functionalization of fullerenes and lithium encapsulated fullerene as well as exploring the reaction mechanism.Meanwhile,the obtained products has been further applied to find their availability in perovskite solar cells.The primary results are presented as follows:Efficient octa-substitution reaction took place on octabromofullerene C60Br8 with alcohols or anisole in the presence of silver triflate to produce octaalkoxy and octaaryl fullerenes in up to 79%yield in retention of the C2v-symmetry.The lowest unoccupied molecular orbital(LUMO)level was widely tunable because of accumulated substituents effects from the eight addends.The LUMO energy difference between C60(OCH2CCl3)8 and C60(C6H4-OMe-4)8 were 0.53 eV,representing low-LUMO and high-LUMO fullerenes.Dynamic light scattering measurements revealed single molecular dispersion of these octa-substituted compounds both in toluene and in dichloromethane at low concentrated condition.This phenomenon is attributed to polar and non-polar hemispheres of these molecules.A highly efficient CuBr2 promoted one-step direct oxidation of alkoxy to ketone has been achieved for the first time.The mechanistic studies unveiled that fullerene can behave as an electron-pool efficiently handling electron transfer,so that proceeds the direct oxidation of alkoxy group.Moreover,[60]fullerene-fused ketones were produced in high yields more than 90%with excellent functional group tolerance,providing an efficient synthetic strategy for[60]fullerene-fused ketones.Li+possesses the highest charge density among alkali-metal ions,which is expected to exhibit the strongest Lewis acidity.Yet,its Lewis acidity is limited because of interaction with counter anions and solvation.Here we kinetically investigated the catalytic effect of "naked" Li+via monitoring the transformation reaction from[5,6]-to[6,6]-Li+@PCBM.The kinetic parameters were determined experimentally,revealed ca.700-fold faster reaction rate at 423 K than empty PCBM corresponded to lowering the activation energy by 57.4 kJ mol-1.We compared both internal and external Li+to prove that the encapsualted Li+in C60 can be considered as solvation free Li+,and can form altimate 1 to 1 complex with the substrate,thereby it could show higher effect than usual Li+Lewis acid.We conjecture that our results will be important to help in the design of new Lewis-acid-catalyzed reactions with very high efficiency.After that,the neutral lithium ion phenyl-C61-butyric acid isomethyl ester obtained by the reduction reaction was used as electron transport layer in the perovskite solar cell and achieved a PCE of 9.6%.