Toluene Processed All-Polymer Solar Cells with 18%Efficiency and Enhanced Stability Enabled by Solid Additive:Comparison Between Sequential-Processing and Blend-Casting

The emergence of polymerized small molecule acceptors(PSMAs)has significantly improved the performance of all-polymer solar cells(all-PSCs).However,the pace of device engineering lacks behind that of materials development,so that a majority of the PSMAs have not fulfilled their potentials.Furthermore,most high-performance all-PSCs rely on the use of chloroform as the processing solvent.For instance,the recent highperformance PSMA,named PJ1-γ,with high LUMO,and HOMO levels,could only achieve a PCE of 16.1%with a high-energy-level donor(JD40)using chloroform.Herein,we present a methodology combining sequential processing(SqP)with the addition of 0.5%wt PC_(71)BM as a solid additive(SA)to achieve an impressive efficiency of 18.0%for all-PSCs processed from toluene,an aromatic hydrocarbon solvent.Compared to the conventional blend-casting(BC)method whose best efficiency(16.7%)could only be achieved using chloroform,the SqP method significantly boosted the device efficiency using toluene as the processing solvent.In addition,the donor we employ is the classic PM6 that has deeper energy levels than JD40,which provides low energy loss for the device.We compare the results with another PSMA(PYF-T-o)with the same method.Finally,an improved photostability of the SqP devices with the incorporation of SA is demonstrated.

Optimizing the power conversion processes in diluted donor/acceptor heterojunctions towards 19.4%efficiency all-polymer solar cells

All polymer solar cells(all-PSCs)promise mechanically-flexible and morphologically-stable organic photovoltaics and have aroused increased interests very recently.However,due to their disorderly conformation structures within the photoactive film,inefficient charge generation and carrier transport are observed which lead to inferior photovoltaic performance compared to smaller molecular acceptor-based photovoltaics.Here,by diluting PM6 with a cutting-edge polymeric acceptor PY-IT and diluting PY-IT with PM6 or D18,donor-dominating or acceptor-dominating heterojunctions were prepared.Synchrotron X-ray and multiple spectrometer techniques reveal that the diluted heterojunctions receive increased structural order,translating to enhanced carrier mobility,improved exciton diffusion length,and suppressed non-radiative recombination loss during the power conversion.As the results,the corresponding PM6+1%PY-IT/PY-IT+1%D18 and PM6+1%PY-IT/PY-IT+1%PM6 devices fabricated by layer-by-layer deposition received superior power conversion efficiency(PCE)of 19.4%and 18.8%respectively,along with enhanced operational lifetimes in air,outperforming the PCE of 17.5%in the PM6/PY-IT reference device.

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.

All-Polymer Solar Cells and Photodetectors with Improved Stability Enabled by Terpolymers Containing Antioxidant Side Chains

It is of vital importance to improve the long-term and photostability of organic photovoltaics,including organic solar cells(OSCs)and organic photodetectors(OPDs),for their ultimate industrialization.Herein,two series of terpolymers featuring with an antioxidant butylated hydroxytoluene(BHT)-terminated side chain,PTzBI-EHp-BTBHTx and N2200-BTBHTx(x=0.05,0.1,0.2),are designed and synthesized.It was found that incorporating appropriate ratio of benzothiadiazole(BT)with BHT side chains on the conjugated backbone would induce negligible effect on the molecular weight,absorption spectra and energy levels of polymers,however,which would obviously enhance the photostability of these polymers.Consequently,all-polymer solar cells(all-PSCs)and photodetectors were fabricated,and the all-PSC based on PTzBI-EHp-BTBHT0.05:N2200 realized an optimal power conversion efficiency(PCE)approaching~10%,outperforming the device based on pristine PTzBI-EHp:N2200.Impressively,the all-PSCs based on BHT-featuring terpolymers displayed alleviated PCEs degradation under continuous irradiation for 300 h due to the improved morphological and photostability of active layers.The OPDs based on BHT-featuring terpolymers achieved a lower dark current at−0.1 bias,which could be stabilized even after irradiation over 400 h.This study provides a feasible approach to develop terpolymers with antioxidant efficacy for improving the lifetime of OSCs and OPDs.

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.

Non-conjugated terpolymer acceptors for highly efficient and stable lager-area all-polymer solar cells

All-polymer solar cells(all-PSCs)have made significant progress recently,but few studies have been conducted to investigate the lab-to-manufacturing translation from the spin-coating method to the printing process.Here,the random copolymerization method and non-conjugated backbone approach are integrated to manipulate the morphology and photoelectric properties of the active layer for large-area printed all-PSCs.A series of non-conjugated terpolymer acceptors PYSe-TC_(6)T(x)(x=5,10,and 20,refers to the molar ratio of TC_(6)T unit)are developed by covalently introducing non-conjugated unit TC_(6)T into the PYSe host bipolymer by random copolymerization.The spin-coated PYSe-TC_(6)T(10)-based all-PSC demonstrates the best power conversion efficiency(PCE)of 13.54%,superior to the PYSe-based one(12.45%).More intriguingly,morphological studies reveal that a combination of the random polymerization and non-conjugated backbone strategy can effectively prevent the active layer from overaggregation and improve the film quality during the printing process,thereby minimizing the efficiency and technology gap between spin-coated small-area devices and blade-coated large-area devices.By directly using the same preparation condition of spin-coating,the blade-coated small-area(0.04 cm^(2))delivers a PCE of 12.83%and the large-area(1.21 cm^(2))device achieves a PCE of 11.96%with a small PCE loss.Both PCE value and PCE loss are one of the most outstanding performances of the bladecoated all-PSCs.These findings reveal that a combination of the non-conjugated flexible backbone with random copolymerization to develop non-conjugated terpolymers is an attractive design concept to smoothly realize the lab-to-manufacturing translation.

A new low-bandgap polymer acceptor based on benzotriazole for efficient all-polymer solar cells

The rational design of polymer acceptors with strong and broad absorption is critical to improve photovoltaic performance.In this work,a new polymer acceptor PY9-T based on heptacyclic benzotriazole(Y9-C16)as a building block and thiophene unit as the linking unit was synthesized,which exhibited a low bandgap(1.37 eV)and a high extinction coefficient of the neat film(1.44×10^(5) cm^(−1)).When PY9-T was blended with the wide bandgap polymer donor PBDB-T,the all-polymer solar cells(APSCs)showed a high power conversion efficiency(PCE)of 10.45%with both high open circuit voltage of 0.881 V and short-circuit current density of 19.82 mA/cm^(2).In addition,APSCs based on PY9-T show good thermal stability,as evidenced by slight changes morphologies when annealed at 100℃.These results suggest that Y9-C16 provides a new building block to develop efficient and stable polymer acceptors.

Optimizing the morphology of all-polymer solar cells for enhanced photovoltaic performance and thermal stability

Due to the complicated film formation kinetics, morphology control remains a major challenge for the development of efficient and stable all-polymer solar cells(all-PSCs). To overcome this obstacle, the sequential deposition method is used to fabricate the photoactive layers of all-PSCs comprising a polymer donor PTzBI-oF and a polymer acceptor PS1. The film morphology can be manipulated by incorporating amounts of a dibenzyl ether additive into the PS1 layer. Detailed morphology investigations by grazing incidence wide-angle X-ray scattering and a transmission electron microscope reveal that the combination merits of sequential deposition and DBE additive can render favorable crystalline properties as well as phase separation for PTzBI-oF:PS1 blends. Consequently, the optimized all-PSCs delivered an enhanced power conversion efficiency(PCE) of 15.21%along with improved carrier extraction and suppressed charge recombination. More importantly, the optimized all-PSCs remain over 90% of their initial PCEs under continuous thermal stress at 65 °C for over 500 h. This work validates that control over microstructure morphology via a sequential deposition process is a promising strategy for fabricating highly efficient and stable all-PSCs.

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.

11.2% Efficiency all-polymer solar cells with high open-circuit voltage

Herein,we fabricated all-polymer solar cells(all-PSCs)based on a fluorinated wide-bandgap p-type conjugated polymer PM6 as the donor,and a narrow bandgap n-type conjugated polymer PZ1 as the acceptor.In addition to the complementary absorption and matching energy levels,the optimized blend films possess high cystallinity,predominantly face-on stacking,and a suitable phase separated morphology.With this active layer,the devices exhibited a high Vocof 0.96 V,a superior Jscof 17.1 mA cm^-2,a fine fill factor(FF)of 68.2%,and thus an excellent power conversion efficiency(PCE)of 11.2%,which is the highest value reported to date for single-junction all-PSCs.Furthermore,the devices showed good storage stability.After 80 d of storage in the N2-filled glovebox,the PCE still remained over 90%of the original value.Large-area devices(1.1 cm^2)also demonstrated an outstanding performance with a PCE of 9.2%,among the highest values for the reported large-area all-PSCs.These results indicate that the PM6:PZ1 blend is a promising candidate for scale-up production of large area high-performance all-PSCs.

Conjugated polymers containing B←N unit as electron acceptors for all-polymer solar cells

Polymer electron acceptors are the key materials in all-polymer solar cells(all-PSCs).In this review,we focused on introducing the principle of boron-nitrogen coordination bond(B←N),and summarizing our recent research on polymer electron acceptors containing B←N unit for efficient all-PSC devices.Two approaches have been reported to design polymer electron acceptors using B←N unit.One is to replace a C-C unit by a B←N unit in conjugated polymers to transform a polymer electron donor to a polymer electron acceptor.The other approach is to construct novel electron-deficient building block based on B←N unit for polymer electron acceptors.The polymer electron acceptors containing B←N unit showed tunable lowest unoccupied molecular orbital(LUMO) energy levels and exhibited excellent all-PSC device performance with power conversion efficiency of exceeding6%.These results indicate that organic boron chemistry is a new toolbox to develop functional polymer materials for optoelectronic device applications.

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.

15.4% Efficiency all-polymer solar cells

We report all-polymer solar cells(All-PSCs) with record-high power conversion efficiency(PCE) through tuning the molecular weights of the polymer donor(PBDB-T) to form optimal active layer morphology. By combining the polymer donors with a newly reported polymer acceptor(PJ1), an unprecedented high PCE of 15.4% and fill factor over 75% were achieved for the AllPSCs with the medium molecular weight polymer donor(PBDB-TMW), which is the highest value for All-PSCs reported so far.Detailed morphology investigation revealed that the proper phase separation in the PBDB-TMW:PJ1 blend should account for the superior device performance as PBDB-TMW exhibits appropriate miscibility with the polymer acceptor PJ1. These results demonstrated that the device performance of All-PSCs could be fully comparable to that of small molecular acceptor-based PSCs. The formation of optimized morphology via precise control of molecular weights of polymer donors and acceptors is crucial to achieve this goal.

High-performance all-polymer solar cells with only 0.47 eV energy loss

The field of all-polymer solar cells(all-PSCs)has experienced rapid development during the past few years,mainly driven by the development of efficient polymer acceptors.However,the power conversion efficiencies(PCEs)of the all-PSCs are still limited by insufficient light absorption of the donor/acceptor blend and large energy loss in devices.We herein designed a polymer acceptor PYT1 constructed n-type molecular acceptor Y5-C20 as the key building block and blended it with a polymer donor PM6 to obtain an all-polymer photoactive layer.The optimized PM6:PYT1 all-PSCs achieved a record higher PCE of 13.43%with a very low energy loss of 0.47 eV and a photoresponse of up to 900 nm compared with the Y5-C20 based device with a best PCE of 9.42%.Furthermore,the PCEs of the PM6:PYT1 all-PSCs are relatively insensitive to the 1-chloronaphthalene(CN)additive contents and active layer thickness.Our results also highlight the effect of CN additive on PM6:PYT1 morphology,i.e.,charge generation,and transport find an optimized balance,and radiative and non-radiative loss is simultaneously reduced in the blend.This work promotes the development of high-performance polymer acceptors and heralds a brighter future of all-PSCs for commercial applications.

Over 16% efficiency all-polymer solar cells by sequential deposition

All-polymer solar cells(all-PSCs) have received extensive attention due to their excellent mechanical robustness and performance stability. However, the power conversion efficiency(PCE) of all-PSCs still lags behind those of organic solar cells(OSCs)based on non-fullerene small molecule acceptors. Herein, we report highly efficient all-PSCs via sequential deposition(SD) with donor and acceptor layers coated sequentially to optimize the film microstructure. Compared with the bulk heterojunction(BHJ)all-PSCs, an optimized morphology with vertical component distribution was achieved for the SD-processed all-PSCs due to the synergistic effect of swelling of polymer films and using additive. Such strategy involves using chlorobenzene as the first layer processing-solvent for polymer donor, chloroform as the second processing-solvent for polymer acceptor with trace 1-chloronaphthalene, efficiently promoting exciton dissociation and charge extraction and reducing trap-assisted recombination.Consequently, over 16% all-PSCs fabricated via SD method was realized for the first time, which is much higher than that(15.2%) of its BHJ counterpart and also among the highest PCEs in all-PSCs. We have further demonstrated the generality of this approach in various all-polymer systems. This work indicates that the SD method can yield excellent all-PSCs and provides a facile approach to fabricating high-performance all-PSCs.

Polymerizing small molecular acceptors for efficient all-polymer solar cells

All-polymer solar cells(all-PSCs)have received attention due to their morphological stability under thermal and mechanical stresses.Currently,the highest reported power conversion efficiency of all-PSCs is over 17%,achieved by utilizing polymerized small molecular acceptors(PSMAs).However,the need for higher regiospecificity to avoid forming isomers during polymerization of SMAs still challenges the further applications of all-PSCs.From this perspective,we focus on some recent studies and highlight the importance of controlling the regioregularity of PSMAs.In particular,integrating PSMAs with regioregularity endows the polymer acceptors with good absorption,superior backbone ordering,and optimal blend morphology compared with those obtained from regiorandom one.Moreover,the distinctive features that are derived from these regioregular PSMAs,such as the possibility of repeatable synthesis and reproducible device performance,herald a brighter future for scaling-up and commercializing all-PSCs.We expect this integrated strategy will inspire researchers to devote more efforts to further narrow the efficiency gap between the PSCs based on SMAs and PSMAs.Finally,we discuss the existing challenges and future prospects of PSMAs as new platform for further advancing 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 chlorinated polymer promoted analogue co-donors for efficient ternary all-polymer solar cells

The efficient ternary all-polymer solar cells(PSCs) are designed and fabricated, using a polymer acceptor of NDP-V-C7 and analogue co-donors containing a chlorinated polymer PBCl T and classical PTB7-Th. PBCl T and PTB7-Th possess very similar chemical structure and matched energy levels to form the cascade of the co-donors. Meanwhile, benefiting from those analogous polymer structures, there is little influence of the morphology in blend film compared to their pristine polymer films. The binary PBCl T:NDP-V-C7 devices exhibit a high open-circuit voltage(V_(oc)) due to the deep HOMO level of PBCl T. The V_(oc)of all-PSCs could be finely manipulated by adjusting the content of PBCl T in blend film. The ternary all-PSCs have the more balanced charge mobility and prolonged carrier lifetime compared to the binary devices. The PBCl T also help improve the miscibility of ternary blend and suppress crystallization in films, bringing about favorable morphology with appropriate orientation and surface roughness in blend film. With the optimal processing, the champion ternary all-PSCs obtain a high PCE of 9.03%, which is about 10% enhancement compared to that of binary device. The results indicate that the ternary approach using analogue co-donors is a practical method to enhance the performance of 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.

Achieving Efficient Thick Film All-polymer Solar Cells Using a Green Solvent Additive

Adva nces in orga nic photovoltaic tech no logies have been geared toward industrial high-throughput printing manufacturing,which requires in sensitivity of photovoltaic performance reg a rd i ng to the light-harvesting layer thickness.However,the thickness of light-harvesti ng layer for all polymer solar cells(all-PSCs)is often limited to about 100 nm due to the dramatically decreased fill factor upon increasing film thickness,which hampers the light harvesting capability to in crease the power con versio n efficie ncy,and is un favorable for fabricating large-area devices.Here we dem on strate that by tuning the bulk heterojuncti on morphology using a non-halogenated solvent,cyclopentyl methyl ether,in the presence of a gree n solve nt additive of dibenzyl ether,the power con versio n efficie ncy of all-PSCs with photoactive layer thick nesses of over 500 nm reached an impressively high value of 9%.The gen eric applicability of this gree n solvent additive to boost the power conversion efficiency of thick-film devices is also validated in various bulk heterojunction active layer systems,thus representing a promising approach for the fabrication of all-PSCs toward industrial production,as well as further commercialization.