A new perspective to develop regiorandom polymer acceptors with high active layer ductility,excellent device stability,and high efficiency approaching 17%

The recently reported efficient polymerized small-molecule acceptors(PSMAs)usually adopt a regioregular backbone by polymerizing small-molecule acceptors precursors with a low-reactivity 5-brominated 3-(dicyanomethylidene)indan-1-one(IC)end group or its derivatives,leading to low molecular weight,and thus reduce active layer mechanical properties.Herein,a series of newly designed chlorinated PSMAs originating from isomeric IC end groups are developed by adjusting chlorinated positions and copolymerized sites on end groups to achieve high molecular weight,favorable intermolecular interaction,and improved physicochemical properties.Compared with regioregular PY2Se-Cl-o and PY2Se-Cl-m,regiorandom PY2Se-Cl-ran has a similar absorption profile,moderate lowest unoccupied molecular orbital level,and favorable intermolecular packing and crystallization properties.Moreover,the binary PM6:PY2Se-Cl-ran blend achieves better ductility with a crack-onset strain of 17.5% and improved power conversion efficiency(PCE)of 16.23% in all-polymer solar cells(all-PSCs)due to the higher molecular weight of PY2Se-Cl-ran and optimized blend morphology,while the ternary PM6:J71:PY2Se-Cl-ran blend offers an impressive PCE approaching 17% and excellent device stability,which are all crucial for potential practical applications of all-PSCs in wearable electronics.To date,the efficiency of 16.86% is the highest value reported for the regiorandom PSMAs-based all-PSCs and is also one of the best values reported for the all-PSCs.Our work provides a new perspective to develop efficient all-PSCs,with all high active layer ductility,impressive PCE,and excellent device stability,towards practical applications.

Novel polymer acceptors achieving 10.18% efficiency for all-polymer solar cells

Polymer acceptors based on extended fused ring p skeleton has been proven to be promising candidates for all-polymer solar cells(all-PSCs), due to their remarkable improved light absorption than the traditional imide-based polymer acceptors. To expand structural diversity of the polymer acceptors, herein,two polymer acceptors PSF-IDIC and PSi-IDIC with extended fused ring p skeleton are developed by copolymerization of 2,20-((2 Z,20 Z)-((4,4,9,9-tetrahexadecyl-4,9-dihydro-s-indaceno [1,2-b:5,6-b']dithio phene-2,7-diyl)bis(methanylylidene))bis(3-oxo-2,3-dihydro-1 H-indene-2,1-diylidene))dimalononitrile(IDIC-C16) block with sulfur(S) and fluorine(F) functionalized benzodithiophene(BDT) unit and silicon(Si) atom functionalized BDT unit, respectively. Both polymer acceptors exhibit strong light absorption.The PSF-IDIC exhibits similar energy levels and slightly higher absorption coefficient relative to the PSi-IDIC. After blended with the donor polymer PM6, the functional atoms on the polymer acceptors show quite different effect on the device performance. Both of the acceptors deliver a notably high open circuit voltage(V_(OC)) of the devices, but PSi-IDIC achieves higher V OCthan PSF-IDIC. All-PSC based on PM6:PSi-IDIC attains a power conversion efficiency(PCE) of 8.29%, while PM6:PSF-IDIC-based device achieves a much higher PCE of 10.18%, which is one of the highest values for the all-PSCs reported so far. The superior device performance of PM6:PSF-IDIC is attributed to its higher exciton dissociation and charge transport, decreased charge recombination, and optimized morphology than PM6:PSi-IDIC counterpart. These results suggest that optimizing the functional atoms of the side chain provide an effective strategy to develop high performance polymer acceptors for all-PSCs.

Effects of Flexible Conjugation-Break Spacers of Non-Conjugated Polymer Acceptors on Photovoltaic and Mechanical Properties of All-Polymer Solar Cells

All-polymer solar cells(all-PSCs)possess attractive merits including superior thermal stability and mechanical flexibility for large-area roll-to-roll processing.Introducing flexible conjugation-break spacers(FCBSs)into backbones of polymer donor(P_(D))or polymer acceptor(P_(A))has been demonstrated as an efficient approach to enhance both the photovoltaic(PV)and mechanical properties of the all-PSCs.However,length dependency of FCBS on certain all-PSC related properties has not been systematically explored.In this regard,we report a series of new non-conjugated P_(A)s by incorporating FCBS with various lengths(2,4,and 8 carbon atoms in thioalkyl segments).Unlike com-mon studies on so-called side-chain engineering,where longer side chains would lead to better solubility of those resulting polymers,in this work,we observe that the solubilities and the resulting photovoltaic/mechanical properties are optimized by a proper FCBS length(i.e.,C2)in P_(A) named PYTS-C2.Its all-PSC achieves a high efficiency of 11.37%,and excellent mechanical robustness with a crack onset strain of 12.39%,significantly superior to those of the other P_(A)s.These results firstly demonstrate the effects of FCBS lengths on the PV performance and mechanical properties of the all-PSCs,providing an effective strategy to fine-tune the structures of P_(A)s for highly efficient and mechanically robust PSCs.

PY-IT,an Excellent Polymer Acceptor

All-polymer solar cells(all-PSCs)have attracted considerable attention due to their inherent advantages over other types of organic solar cells,including superior optical and thermal stability,as well as exceptional mechanical durability.Recently,all-PSCs have experienced remarkable advancements in device performance thanks to the invention of polymerized small-molecule acceptors(PSMAs)since 2017.Among these PSMAs,PY-IT has garnered immense interest from the scientific community due to its exceptional performance in all-PSCs.In this review,we presented the design principles of PY-IT and discussed the various strategies employed in device engineering for PY-IT-based all-PSCs.These strategies include additive and interface engineering,layer-by-layer processing methods,meniscus-assisted coating methods,and ternary strategy.Furthermore,this review highlighted several novel polymeric donor materials that are paired with PY-IT to achieve efficient all-PSCs.Lastly,we summarized the inspiring strategies for further advancing all-PSCs based on PY-IT.These strategies aim to enhance the overall performance and stability of all-PSCs by exploring new materials,optimizing device architectures,and improving fabrication techniques.By leveraging these approaches,we anticipate significant progress in the development of all-PSCs and their potential as a viable renewable energy source.

8.30%Efficiency P3HT-based all-polymer solar cells enabled by a miscible polymer acceptor with high energy levels and efficient electron transport

P3HT stands out from numerous polymer donors owing to the merits of low cost and high scalability of synthesis.However,the photovoltaic performance of P3HT-based blends lags significantly behind the state-of-the-art systems,especially for all-polymer solar cells(APSCs) that generally show efficiency of around 3%–4% due to the lack of matched polymer acceptors.Herein,a polymer acceptor,named IDTBTC8-CN,was designed and synthesized with indacenodithiophene(IDT) and mono-cyano(CN)-substituted benzothiadiazole(BT-CN) as building blocks.Introducing a CN group endowed the polymer with decreased bandgap,and apparent n-type charge transport character despite the relatively high energy levels.Additionally,IDTBTC8-CN showed largely improved miscibility with P3HT,compared with that of BT-based control polymer IDTBTC8.The high miscibility between P3HT and IDTBTC8-CN as well as the amorphous aggregation behavior of IDTBTC8-CN enabled a broad manipulation room for the blend film to acquire favorable morphology.Eventually,a champion efficiency of 8.30% was achieved,in sharp contrast to that of the IDTBTC8-based system(1.21%).Such efficiency is a new record for P3HT-based APSCs reported so far.Moreover,P3HT:IDTBTC8-CN blend film also exhibited excellent mechanical robustness.This study implies the guidance of molecular design of the polymer acceptors and morphology control for P3HT-based APSCs.

Recent Research Progress of n-Type Conjugated Polymer Acceptors and All-Polymer Solar Cells

The active layer of all polymer solar cells(all-PSCs)is composed of a blend of a p-type conjugated polymer(p-CP)as donor and an n-type conjugated polymer(n-CP)as acceptor.All-PSCs possess the advantages of light weight,thin active layer,mechanical flexibility,low cost solution processing and high stability,but the power conversion efficiency(PCE)of the all-PSCs was limited by the poor photovoltaic performance of the n-CP acceptors before 2016.Since the report of the strategy of polymerized small molecule acceptors(PSMAs)in 2017,the photovoltaic performance of the PSMA-based n-CPs improved rapidly,benefitted from the development of the A-DA’D-A type small molecule acceptors(SMAs).PCE of the all-PSCs based on the PSMA acceptors reached 17%-18%recently.In this review article,we will introduce the development history of the n-CPs,especially the recent research progress of the PSMAs.Particularly,the structure-property relationship of the PSMAs is introduced and discussed.Finally,current challenges and prospects of the n-CP acceptors are analyzed and discussed.

An asymmetric non-fused electron-deficient building block for low-cost polymer acceptor in all-polymer solar cells

The development of polymerized fused-ring small molecule acceptors(FRA-PAs) has boosted the performance of all-polymer solar cells(all-PSCs).However,these FRA-PAs suffer from lengthy synthesis steps and high production costs due to the high degree of synthetic complexity for fused-ring small molecule acceptors(FRAs).Furthermore,most FRA-PAs exhibit strong batch-to-batch variation,limiting further industrial applications.Herein,we designed and synthesized asymmetric non-fused electron-deficient building block TIC-Br with a simple structure(only three synthetic steps),showing a planar configuration,excellent electron affinity,and large dipole moment.A simple polymer acceptor PTIB was further developed by polymerization of TIC-Br and sensitized fluorinated-thienyl benzodithiophene(BDT-TF-Sn).PTIB exhibits a broad absorption from 300 to 800 nm,a suitable lowest unoccupied molecular orbital(LUMO) energy level of-3.86 e V,and moderate electron mobility(1.02×10^(-4)cm^(2)V^(-1)s^(-1)).When matched with PM6,the device achieved the best PCE of 10.11%with a high V_(OC) of 0.97 V,which is one of the highest among those reported all-PSCs.More importantly,PTIB exhibits a lower synthetic complexity index(SC=35.0%)and higher figure-of-merit values(FOM=29.0%) than all the reported high-performance PAs.The polymer also exhibits excellent batch-to-batch reproducibility and great potential for scale-up fabrication.This study indicates that TIC-Br is a promising building block for constructing low-cost polymer acceptors for large-scale applications in all-PSCs.

All-Polymer Solar Cells with Perylenediimide Polymer Acceptors

Four polymers based on perylenediimide co-polymerized with thiophene, bithiophene, selenophone and thieno[3,2-b]thiophene were investigated as the acceptor materials in all-polymer solar cells. Two different donor polymers, poly[4,8-bis（5-（2-ethylhexyl）thiophen-2-yl）benzo[ 1,2-b;4,5-b＇]dithiophene-2,6-diyl-alt-（4-（2-ethylhexyl）-3-fluorothieno[3,4- b]thiophene）-2-carboxylate-2,6-diyl] （PTB7-Th） and poly[（5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl）-alt-（3,3＇-di（2- dodecyltetradecyl）-2,2＇;5＇,2＂;5＂,2＇-quaterthiophen-5,5＇＂-diyl）] （PffBT4T-2DT）, with suitably complementary absorption spectra and energy levels were applied and examined. Among all different donor-acceptor pairs studied here, the combination of PTB7-Th：poly[NN-bis（1-hexylheptyl）-3,4,9,10-pery,enediimide-1,6/1,7-diyl-alt-2,5-thiophene] （PDI-Th） exhibited the best power conversion efficiency （PCE） of 5.13%, with open-circuit voltage （Vo：） = 0.79 lV, short-circuit current density （Jsc） = 12.35 mA.cm-2 and fill-factor （FF） = 0.52. The polymer of PDI-Th acceptor used here had a regio-irregular backbone, conveniently prepared from a mixture of 1,6- and 1,7-dibromo-PDI. It is also noteworthy that neither additive nor post- treatment is required for obtaining such a cell performance.

High-performance all-polymer solar cells enabled by a novel low bandgap non-fully conjugated polymer acceptor

The non-fully conjugated polymer as a new class of acceptor materials has shown some advantages over its small molecular counterpart when used in photoactive layers for all-polymer solar cells(all-PSCs),despite a low power conversion efficiency(PCE)caused by its narrow absorption spectra.Herein,a novel non-fully conjugated polymer acceptor PFY-2TS with a low bandgap of~1.40 eV was developed,via polymerizing a largeπ-fused small molecule acceptor(SMA)building block(namely YBO)with a non-conjugated thioalkyl linkage.Compared with its precursor YBO,PFY-2TS retains a similar low bandgap but a higher LUMO level.Moreover,compared with the structural analog of YBO-based fully conjugated polymer acceptor PFY-DTC,PFY-2TS shows a similar absorption spectrum and electron mobility,but significantly different molecular crystallinity and aggregation properties,which results in optimal blend morphology with a polymer donor PBDB-T and physical processes of the device in all-PSCs.As a result,PFY-2TS-based all-PSCs achieved a PCE of 12.31%with a small energy loss of 0.56 eV enabled by the reduced non-radiative energy loss(0.24 eV),which is better than that of 11.08%for the PFY-DTC-based ones.Our work clearly demonstrated that non-fully conjugated polymers as a new class of acceptor materials are very promising for the development of high-performance all-PSCs.

Low-cost polymer acceptors with noncovalently fused-ring backbones for efficient all-polymer solar cells

The polymerization of fused-ring acceptors(FRAs) to afford their corresponding polymeric acceptors for high-performance all-polymer solar cells(all-PSCs) has achieved remarkable progress in the past few years.However,due to the high degree of synthetic complexity for the monomer,the high-cost of these polymeric acceptors may limit their commercial applications.Thus,it is urgent to develop inexpensive and high-performance polymeric acceptors for all-PSCs.Herein,two novel polymeric acceptors(PBTzO and PBTzO-2F) have been designed and synthesized by copolymerization of noncovalently fused ring acceptors(NFRAs),which were employed in all-PSCs for the first time.Upon introducing the “noncovalently conformational locks(NoCLs)” in the backbone and selective fluorination of the end-group,photophysical and electrical properties,and solidstate packing properties of the NFRAs have been rationally tuned.As a result,the PBDB-T:PBTzO-2F based devices presented an excellent power conversion efficiency(PCE) of 11.04%,much higher than that of PBTzO based ones due to the increased charge generation and extraction,improved hole transfer and carrier mobilities,and reduced energy loss.More importantly,PBTzO-2F exhibited a much lower synthetic complexity(SC) index and higher figure-of-merit(FOM) values than the high-performance fused-ring acceptor based polymer acceptors(FRA-PAs) due to the simpler structures and more effective synthesis.This contribution provided a novel idea to achieve low-cost and high-performance all-PSCs.

Reducing energy loss via tuning energy levels of polymer acceptors for efficient all-polymer solar cells

The open-circuit voltage(Voc) of all-polymer solar cells(all-PSCs) is typically lower than 0.9 V even for the most efficient ones.Large energy loss is the main reason for limiting Voc and efficiency of all-PSCs. Herein, through materials design using electron deficient building blocks based on bithiophene imides, the lowest unoccupied molecular orbital(LUMO) energy levels of polymer acceptors can be effectively tuned, which resulted in a reduced energy loss induced by charge generation and recombination loss due to the suppressed charge-transfer(CT) state absorption. Despite a negligible driving force, all-PSC based on the polymer donor and acceptor combination with well-aligned energy levels exhibited efficient charge transfer and achieved an external quantum efficiency over 70% while maintaining a large Voc of 1.02 V, leading to a 9.21% efficiency. Through various spectroscopy approaches, this work sheds light on the mechanism of energy loss in all-PSCs, which paves an avenue to achieving efficient all-PSCs with large Voc and drives the further development of all-PSCs.

16.3%Efficiency binary all-polymer solar cells enabled by a novel polymer acceptor with an asymmetrical selenophene-fused backbone

Despite the significant progress made recently in all-polymer solar cells(all-PSCs),it is still quite challenging to achieve high open-circuit voltage(V_(oc))and short-circuit current density(J_(sc))simultaneously in order to further improve their performance.The recent strategy of using selenophene to replace thiophene on the Y6 based polymer acceptors has resulted in significantly improved J_(sc)s of the resulting all-PSCs.However,such modifications have also depressed V_(oc),which compromises the overall performance of the devices.Herein,we present the design and synthesis of a novel polymer acceptor,PYT-1S1Se,created by inserting an asymmetrical selenophene-fused framework to precisely manipulate optical absorption and electronic properties.Compared with the selenium-free analog,PYT-2S,and symmetrical selenium-fused analog,PYT-2Se,the PYT-1S1Se derived all-PSCs not only deliver optimized J_(sc)(24.1 mA cm^(−2))and V_(oc)(0.926 V)metrics,but also exhibit a relatively low energy loss of 0.502 eV.Consequently,these devices obtain a record-high power conversion efficiency(PCE)of 16.3%in binary all-PSCs.This work demonstrates an effective molecular design strategy for balancing the trade-off between V_(oc) and J_(sc) to achieve highefficiency all-PSCs.

Printable and stable all-polymer solar cells based on non-conjugated polymer acceptors with excellent mechanical robustness

All-polymer solar cells(all-PSCs)trigger enormous commercial applications,and great progress has been made in recent years.However,from small-area devices to large-area modules,the poor adaption of the materials for printing methods and the large efficiency loss are still great challenges.Herein,three novel non-conjugated polymer acceptors(PTH-Y,PTClm-Yand PTClo-Y)are developed for all-PSCs.It can be found that non-conjugated polymer acceptors can effectively minimize the technique and efficiency gaps between small-area spin-coating and large-area blade-printing method,which can facilitate the preparation of large-area flexible device.By directly inheriting the spin-coating condition,the blade-coating processed device based on PTCloY achieves an impressive power conversion efficiency(PCE)of 12.42%,comparable to the spin-coating processed one(12.74%).Such a non-conjugated polymer system also can well tolerate large-scale preparation and flexible substrate.Notable PCE of 11.94%for large-area rigid device and 11.56%for large-area flexible device are obtained,which is the highest value for large-area flexible all-PSCs fabricated by blade-coating.In addition,the non-conjugated PTClo-Y-based devices show excellent thermal stability and mechanical robustness.These results demonstrate that the non-conjugated polymer acceptors are potential candidates for the fabrication of highly-efficient,large-area and robust flexible all-PSCs by printing methods.

A Near-Infrared Polymer Acceptor Enables over 15%Efficiency for All-Polymer Solar Cells

Finding effective molecular design strategies to enable efficient charge generation,high charge transport,and small energy loss is a longstanding challenge for developing high-performance all-polymer solar cells(all-PSCs).Here,we designed and synthesized a fused-aromatic-ring-constructed near-infrared(NIR)polymer acceptor(PA)PYT-Tz with fused-ring benzotriazole(BTz)-based A’-DAD-A’structure as electron-deficient-core,n-nonane as alkyl-side-chain and thiophene asπ-bridge,and achieved a power conversion efficiency(PCE)of 15.10%for the all-PSCs with PYT-Tz as acceptor and a wide-bandgap PBDB-T as donor.A control PA PYT reported by our lab recently was introduced for investigating the synergistic effect of the electron-deficient-core and alkyl-side-chain on the optoelectronic properties and photovoltaic performance of the n-type PAs.Compared with PYT,the designed PYT-Tz exhibits intense and red-shifted absorption,upshifted energy levels,high electron mobility and ordered molecular packing in the active layers,and,blended with PBDB-T,yields the efficient hole injection,ultrafast charge generation,and the decreased non-radiative recombination loss of 0.17 eV.Of note is that the PCE of 15.10%is one of the highest PCE values for an all-PSC reported to date.Our results indicate BTz-based fused-aromatic-ring-constructed PAs are promising NIR acceptors in the all-PSCs.

Organic solar cells based on small molecule donor and polymer acceptor

Small molecule donor/polymer acceptor(SD/PA)-type organic solar cells(OSCs)have attracted widespread attention in recent years due to the continuing power conversion efficiency(PCE)growth,near 10%,and the excellent thermal stability for the practical applications.However,the development of SD/PA-type OSCs lags far behind that of polymer donor/small molecule acceptor(PD/SA)-type OSCs,which are also based on the combination of small molecule and polymer,with the PCEs exceeding 18%.The reasons accounting for this great gap are well worth exploring.In this review,we have analyzed the key factors affecting the photovoltaic performances of SD/PA-type OSCs,systematically summarized the research progress of SD/PA type OSCs in recent years,and put forward our own views on the future development of SD/PA type OSCs.

Nonfused-Core-Small-Molecule-Acceptor-Based Polymer Acceptors for All-Polymer Solar Cells

Polymerizing the narrow bandgap small-molecule architecture with a conjugated linking unit(or called the polymerized small molecule acceptors(PSMAs))is a promising strategy to design polymer acceptors for efficient all polymer solar cells(all-PSCs).Currently,the fused-ring-based small molecule acceptors(SMAs)are preferred monomers to design efficient PSMAs,leaving the challenge of reducing the materials cost.In this work,we firstly employ nonfused-core SMA with simple synthetic procedures to design PSMAs(namely PBTI-H,PBTI-F and PBTI-Cl)to address this issue.Relative to the fused-ring based counterparts,these three PSMAs exhibit much higher figure-of-merit value.Additionally,a power-conversion efficiency of 8.80%is achieved in the PBTI-Cl-based all-PSC.The results offer an attractive approach to design low-cost PSMAs for efficient all-PSCs.

15%Efficiency All-Polymer Solar Cells Based on a Polymer Acceptor Containing B←N Unit

The development of new polymer acceptors strongly paves the power conversion efficiency(PCE)improvement of all polymer solar cells(all-PSCs).Herein,we develop a new polymer acceptor PBN26,which is the alternating copolymer of 2,2′-((2Z,2′Z)-((12,13-bis(2-octyldodecyl)-3,9-diundecyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2″,3″:4′,5′]thieno[2′,3′:4,5]pyrrolo[3,2-g]thieno[2′,3′:4,5]thieno[3,2-b]indole-2,10-diyl)bis(methanylylidene))bis(3-oxo-2,3-dihydro-1 H-indene-2,1-diylidene))dimalononitrile and B←N bridged thienylthiazole(BNTT).The optimized all-PSCs device based on PBN26 exhibits a PCE of 15.09%,which is the highest value of the all-PSCs based on B←N-based polymer acceptors at present.Moreover,we also fabricate an all-PSC module with active area of 10 cm2 by blade coating,which exhibits a PCE of 8.78%.These results prove that polymer acceptors containing B←N units are promising for all-PSC device applications.

Controlling molecular weight of naphthalenediimide-based polymer acceptor P(NDI2OD-T2)for high performance all-polymer solar cells

A widely-used naphthalenediimide （NDI） based electron acceptor P（NDI2OD-T2） with different number- average molecular weight （Mn） of 38 （N2200L）, 56 （N2200M）, 102 （N2200H） kDa were successfully prepared. The effect of molecular-weight on the performance of all-polymer solar cells based on Poly（5-（5-（4,8- bis（ 5-decylthiophen-2-yl ）-6-methylbenzo[1,2-b： 4,5-b＇]dithophen-2-yl ）thiophen-2-yl ）-6,7-difluoro-8- （5-methylthiophen-2-yl）-2,S-bis（3-（octyloxy）phenyl）quinoxaline） （P2F-DE）：N2200 was systematically investigated. The results reveal that N2200 with increased M. show enhanced intermolecular interac- tions, resulting in improved light absorption and electron mobility. However, the strong aggregation trend of N2200H can cause unfavorable morphology for exciton dissociation and carrier transport. The blend film using N2200 with moderate M. actually develops more ideal phase segregation for efficient charge separation and transport, leading to balanced electron/hole mobility and less carrier recombi- nation. Consequently, all-polymer solar cells employing P2F-DE as the electron donor and N2200M as the electron acceptor show the highest efficiency of 4.81%, outperforming those using N2200L （3,07~;） and N2200H （S,92%）. Thus, the Mn of the polymer acceptor plays an important role in all-polymer solar ceils, which allows it to be an effective parameter for the adjustment of the device morphology and efficiency.

Planarized Polymer Acceptor Featuring High Electron Mobility for Efficient All-Polymer Solar Cells

Significant progress has been achieved for all-polymer solar cells(APSCs)in the last few years by the use of polymerized small molecular acceptors(PSMAs).Developing high electron mobility polymer acceptors has been considered a feasible solution to further improve the photovoltaic performance of APSCs and fabricate thick film devices,which contributed to roll-to-roll printing techniques.In this work,we designed and synthesized PSV,an A-DA’D-A small molecule acceptor-based PSMA with the vinyl group as a bridged linkage to reduce the steric hindrance between the 1,1-dicyanomethylene-3-indanone(IC)terminal group.In comparison with the C-C bond linked polymer acceptor PS,PSV exhibits an almost planar conjugated framework and well-ordered molecular stacking in the thin film.Moreover,PSV exhibits superior n-type semiconducting properties with high electron mobility of up to 0.54 cm^(2)·V^(−1)·s^(−1),which is the highest value among reported PSMAs.By utilizing PM6 as a polymer donor,PSV-based blend forms a favorable nanomorphology and exhibits high and well-balanced hole/electron mobilities,which is beneficial for exciton separation and charge transport.Consequently,APSCs based on PM6:PSV achieved high power conversion efficiencies of up to 15.73%,with a simultaneously realized high Voc of 0.923 V,Jsc of 23.2 mA·cm^(-2),and FF of 0.734.Such superior features enable PSV with excellent thickness-insensitive properties and over 13%PCE was obtained at 300 nm.To the best of our knowledge,the high PCE of 15.73%with excellent electron mobility of 0.54 cm^(2)·V^(−1)·s^(−1)is the highest values reported for APSCs.These results point to the great significance of developing polymer acceptors with a high electron mobility for boosting the performance of APSCs.

PHOTOINDUCED CHARGE TRANSFER POLYMERIZATION OF STYRENE INITIATED BY ELECTRON ACCEPTOR

Photoinduced charge transfer polymerization of styrene(St) with electron acceptor as initiator was investigated. In case of fumaronitrile (FN) or maleic anhydride (MA) as initiator the polymerization takes place regularly, whereas the tetrachloro-1,4-benzenequinone (TCQ), 2,3-dichloro-5, 6-dicyano-1, 4-benzenequinone (DDQ). or tetracyano ethylene (TCNE) as initiator the polymerization proceeds reluctantly only after the photoaddition reaction. A mechanism was proposed that free radicals would be formed following the charge and proton transfer in the exciplex formed between St and electron accepters.