Application Of Functional Low Molecular Weight Organic Molecules In Novel Thin Film Solar Cells

As one of the important solutions for solving energy shortage,the two kinds of novel thin film solar cells,dye-sensitized solar cells(DSSCs)and perovskite solar cells(PSCs)have captured increasing attention in recent years.In this work,two-component co-gelator is designed and applied into DSSCs,which retains stability of DSSCs and improves the photovoltaic performce of the devices.Then,a range of amides derivatives and pyridine derivatives are introduced into PSCs,sespectively.The hydrophobic groups and donor-electronpair groups can control the hydrophobic stabilty and process of crystallization kinetics of perovskite films sespectively,which improve stability and photovoltaic performce of PSCs.Therefore,the work can be devided into three parts:(1)Due to the quasi-solid-state electrolyte based DSSCs,which is gelated by single-component low molecular mass organogelator,can achieve poor photovoltaic performance.In this work,the DSSCs are fabricated by the two-component gel electrolyte co-gelated by N,N'-,5-pentanediylbis-dodecanamide and 3-(Boc-amino)pyridine.In comparision with the single-component gel,the two-component gel possesses smaller fibril size,which improves ions transport in electrolyte.Whatsmore,the N-containing heterocycles in 3-(Boc-amino)pyridine can absorb on the surface of the TiO2 film,which decreases electron recombination at the photoelectrode/electrolyte interface.Therefore,the photoelectric conversion efficiency(PCE)of the DSSC increases from 6.19%to 6.74%after adding 3-(Boc-amino)pyridine.Importantly,the two-component gel based QS-DSSCS shows great stability because of the high gel-to-solution transition temperature(Tgel=106?),retaining over 91.6%of its initial PCE value after successive heating at 50? for 1000 h.(2)According to the poor humidity stability of PSCs,a range of amides derivatives with functional groups are introduced into perovskite flims.On the one hand,amide groups in amides derivatives can couple with iodine by hydrogen bonds,which can decrease the distance of two perovskite crystals.On the other hand,alkyl chains in amides derivatives show hydrophobic property,which can improve the humidity-resistance of perovskite films.According to the results which measured in dark without encapsulation over 168h,the PSCs with amides derivatives retained 80%of initial values,while the control PSCs retained 1%of initial value,low molecular weight organic molecules,amides derivatives can improve the humidity-resistance of PSCs.(3)For improving photovoltaic performance and humidity stability of PSCs,Pyridine,4-methylpyridine and 4-tert-butylpyridine as donor-electronpair lewis base additives are introduced into perovskite films.First,lewis bases can form lewis acid-base adducts with PbI2 and contribute to formation of more compact and homogeneous perovskite films,increase the size of perovskite crystal and light absorbing of perovskite films,decrease the density of defect states,and improve the photovoltaic performance of perovskites solar cell.Moreover,the different hydrophobicity of the three additives has different effect on the humidity stability of PSCs,which can be proved by water contacting angle measurement and humidity stability research of PSCs.