Design,Synthesis And Photovoltaic Performance Of Organic Solar Cells Containing Novel Imide Benzotriazole Polymers

As a rising clean energy technique,organic solar cells(OSCs)have drawn significant attention due to their specific advantages such as simple manufacturing procedures,low cost,flexibility,and semi-transparency.Recently,the power conversion efficiency(PCE)of OSCs has been exceeded 17%.However,the light absorption and energy levels of traditional fullerene acceptors are difficult to be regulated,leading to a bottleneck of efficiency for OSCs when matching with narrow band-gap polymer donor materials.In contrast,wide-bandgap polymer donor materials have shown promising prospects in non-fullerene,all-polymer and tandem devices owning to the complementary light absorption features.Inspired by this,researches had been focused on OSCs based on the wide band-gap donor polymers.In this dissertation,we carefully studied the influence of photoactive layer combinations,regioenvironment,and green solvents procesing on the performance of OSCs based on imide-functionalized benzotriazole(Tz BI)-type wide-bandgap polymeric donors.Firstly,we employed two non-fullerene acceptors,BTPT-4F and BTPTT-4F,to match with a wide-gap polymer donor P2F-EHp constructed from Tz BI moiety to prepare high-performance OSCs.By exploring the relationship between the blend film and the device performance,we demonstrated that inhibiting aggregation and controlling phase separation were essential to improve the performance of photovoltaic devices.Then,we introduced a single fluorine atom on the ?-bridge of Tz BI-based polymer to create two regioisomers,PTz BI-p F and PTz BI-d F,and investigated the impact of regio-environment on the performance of relevant solar cell devices.We demonstrated that the fluorination position had great influence on the molecular conformations and aggregation morphologies,resulting in remarkably different absorption spectra and charge carrier mobilities.As a result,the planar one,PTz BI-d F,exhibited a much higher device efficiency of 16.84 % with respect to that of 1.42 % for the twisted counterpart of PTz BI-p F.At last,we designed and synthesized a new Tz BI-polymeric donor,P2F-Si,which had deep highest occupied molecular orbital(HOMO)energy level.When combined with a novel naphthalimide-based polymeric acceptor PNDICl that had an asymmetric structure of chlorination,the resulting blends showed remarkable solubility in various commom-used organic solvents,enabling the feasibility of fabrication of all-polymer solar cells(all-PSCs)by using a green solvent of d-limonene.The resulting d-limoneneprocessed all-PSCs presented an impressively high open-circuit voltage of approaching 1.0 V,corresponding to a very small energy loss of 0.49 e V.Through further morphology optimization by using ?-valerolactone,we demonstrated an impressive device efficiency of 4.2 %,which was among the best photovoltaic performance of devices processed by d-limonene and comparable to that processed by conventional solvent,suggesting the great promise of using greener solvent for fabricating highperformance all-PSCs.