Solution-processed Polymer Solar Cells Research Articles

Efficient inverted PM6:Y6 solar cells with tuned lateral phase separation and vertical composition distribution via bis(5-chlorothiophen-2-yl)alkane additives

Finely controlling the morphology of bulk heterojunction (BHJ) films by additives provides a critical and versatile tool to boost performance of solution processed polymer solar cells (PSCs). In great need are efficient additives that can optimize the arrangement of energetically paired donor and acceptor materials to propel individual photoelectric conversion steps close to unity either in conventional or inverted PSCs. Alternative to the paradigm additives such as 1-chloronaphthlene (CN) etc. for highly efficient conventional PSCs with Y6-type acceptors, herein, bis(5-chlorothiophen-2-yl)alkanes (BCTA-m) with 3 ∼ 6 methylene units (m = 3, 4, 5 and 6) were incorporated as solvent additives to fabricate inverted PM6:Y6 PSCs. The lateral phase separation and vertical composition distribution between PM6 and Y6 were discovered tunable by varying the length (m) of alkanes. The BCTA-4 device offers the maximum power conversion efficiency (PCE) of 15.59%, which is superior to the ones processed from the other BCTA-m (m = 3, 5 and 6) additives and comparable to that of the CN reference (15.62%). The outperformed exciton generation and dissociation, charge transport and suppressed charge recombination are evidently observed within the BCTA-4 device. Furthermore, the lateral phase-separated domain sizes between the pure Y6 (2Rg-Y6) and the PM6:Y6 mixture (ξ) get an optimum ratio. The overwhelmingly vertical distribution of PM6 near the anode is also confirmed in the BCTA-4 device over the ones processed from the other three analogues. This work demonstrates the potential of BCTA-4 additive to realize high-performance inverted PSCs based on Y6-type acceptors.

Graphitic Carbon Nitride Nanosheets: Dual Functional Charge Selective Cathode/Anode Interface Layer for Polymer Solar Cells

Here, we report a systematic study proposing the utilization of graphitic carbon nitride nanosheets (g-C3N4 NS) thin film as a charge-selective cathode/anode interface layer for inverted as well as conventional polymer solar cells. The pristine ITO/g-C3N4 NS thin film-based electrodes were found to have a work function value of approximately 4.43 eV making them a potential candidate as a cathode interface layer for inverted devices. The work function value increased to ∼5.25 eV after UV-ozone treatment, befitting as an anode interface layer for conventional PSCs. The device with g-C3N4 NS as the interface layer exhibited similar short circuit current density for both inverted and conventional device architecture. This confirms the dual functionality of the g-C3N4 NS thin film in terms of charge-selectivity for efficient carrier collection. The overall power conversion efficiency for the two devices was approximately 5.60% and 6.05%, respectively. The UV-ozone treatment seems to alter the work function of g-C3N4 NS thin film by inducing surface dipoles due to the incorporation of oxygen atoms. This results in switching from electron-extracting behavior to hole extraction. Our results demonstrate the dual functional nature of g-C3N4 NS as an interface layer (CIL/AIL) for solution-processable polymer solar cells.

Impact of hybrid plasmonic nanoparticles on the charge carrier mobility of P3HT:PCBM polymer solar cells

The solution processable polymer solar cells have shown a great promise as a cost-effective photovoltaic technology. Here, the effect of carrier mobility changes has been comprehensively investigated on the performance of P3HT:PCBM polymer solar cells using electro-optical coupled simulation regimes, which may result from the embedding of SiO2@Ag@SiO2 plasmonic nanoparticles (NPs) in the active layer. Firstly, the active layer thickness, stemmed from the low mobility of the charge carriers, is optimized. The device with 80 nm thick active layer provided maximum power conversion efficiency (PCE) of 3.47%. Subsequently, the PCE has increased to 6.75% and 6.5%, respectively, along with the benefit of light scattering, near-fields and interparticle hotspots produced by embedded spherical and cubic nanoparticles. The PCE of the devices with incorporated plasmonic nanoparticles are remarkably enhanced up to 7.61% (for spherical NPs) and 7.35% (for cubic NPs) owing to the increase of the electron and hole mobilities to {upmu }_{e}=8times {10}^{-7} ,{text{m}}^{2}/text{V}/text{s} and {upmu }_{h}=4times {10}^{-7} ,{text{m}}^{2}/text{V}/text{s}, respectively (in the optimum case). Furthermore, SiO2@Ag@SiO2 NPs have been successfully synthesized by introducing and utilizing a simple and eco-friendly approach based on electroless pre-treatment deposition and Stober methods. Our findings represent a new facile approach in the fabrication of novel plasmonic NPs for efficient polymer solar cells.

Naphthalenothiophene imide-based polymer exhibiting over 17% efficiency

Summary Developing novel electron-deficient monomers is crucially important for the future development of non-fullerene organic solar cells. Here, we report a new electron-deficient monomer naphthalenothiophene imide (NTI) and NTI-based copolymers PNTB and PNTB-2T. The strong electron-withdrawing ability of NTI could effectively lower the HOMO level of the polymer that facilitates the tuning of the polymer’s physical properties while simultaneously maintaining the low-lying HOMO value. Polymer chains modification by introducing extra thiophenes results in the closed π−π stacking and ordered polymer chain packing of PNTB-2T and is proven to be an effective strategy to increase the device performance. Thus, solar cell devices for PNTB-2T:Y6 exhibit an efficiency of 16.72%, which is further enhanced to 17.35% by the third component PC71BM, whereas that for PNTB:Y6 is only 3.81%. Importantly, PNTB-2T-based devices exhibit excellent batch-to-batch reproducibility. These features make this family of polymer donors very promising and the design strategies will enlighten future development of high-performance polymer donors for organic solar cells (OSC).

A ternary organic solar cell with 15.6% efficiency containing a new DPP-based acceptor

A new non-fullerene small molecule (MPU6) containing thienylethynylselenophene bridges, has been studied as an acceptor along with PC71BM and TDTBTA as a donor in ternary solution-processed bulk heterojunction polymer solar cells, showing a PCE of 15.60%.

A micro-cavity forming electrode with high thermal stability for semi-transparent colorful organic photovoltaics exceeding 13% power conversion efficiency

In this study, we demonstrate a novel micro-cavity forming electrode with a sandwiched structure of Ag/HATCN/Ag. This new electrode presents high transmittance in visible wavelengths and reveals the capability of modulating the wavelength of transmitted light by precisely adjusting the thickness of HATCN interlayer. Notably, the Ag/HATCN/Ag electrode possesses excellent thermal stability that leads to an insignificant peak shift of the transmittance spectrum after thermal aging as exposed to air. This new electrode can be applied to both the solution-processed polymer solar cell (PSC) and thermally evaporated small molecule solar cell (SMSC). The implementation of the Ag/HATCN/Ag electrode for the blue, green, and red PSCs with PM6:Y6 as the photoactive blend results in the power conversion efficiency (PCE) over 13%, representing the highest performance for colorful PSCs ever reported. Significantly, the blue PSC shows the highest PCE up to 13.54% with a maximum transmittance of 15.6%. In addition, vacuum-processed red SMSC based on the active layer composed of DTDCPB:C70 blend shows a PCE and a maximum transmittance of 7.84% and 26.4%, respectively, while the blue and green SMSCs also exhibit PCE higher than 7%. The high PCE and the good transmittance of both the PSC and SMSC imply that the new micro-cavity forming Ag/HATCN/Ag electrode has promising potential in various practical applications.

Water-assisted formation of highly conductive silver nanowire electrode for all solution-processed semi-transparent perovskite and organic solar cells

Transparent conductive electrode (TCE) is an essential part of modern optoelectronic devices. Silver nanowire (AgNW) is regarded as the most promising TCEs, owing to its balanced conductivity and transparency, and solution processability. The use of insulating polyvinyl pyrrolidone (PVP) surfactant limits the conductivity of the final AgNW networks. Herein, by introducing a small amount of deionized water into the AgNWs dispersion in isopropanol (IPA), the conductivity of the spray-coated AgNW electrode was significantly improved. Sheet resistance (Rs) of 27.0 Ω □−1 with transparency of 92% (at 550 nm) was obtained for the AgNW films spray coated from the AgNW ink with 20% water, which is much lower than the IPA-only AgNW film (120.9 Ω □−1 with similar transparency). Morphology analysis confirmed that water is able to wash PVP away from the AgNW surface and promote the formation of AgNW bundles, which increase the conductivity. The optimized AgNW ink was then used for perovskite and polymer solar cells. High power conversion efficiencies of 14.04% for perovskite solar cell and 6.44% for organic solar cells with averaged light transmittance of 21.7% and 33.12% are achieved, respectively, which are among the highest values for all solution-processed semi-transparent perovskite and polymer solar cells.

Research Progress on Polymer Solar Cells Based on PEDOT:PSS Electrodes.

Solution-processed polymer solar cells (PSCs) have attracted dramatically increasing attention over the past few decades owing to their advantages of low cost, solution processability, light weight, and excellent flexibility. Recent progress in materials synthesis and devices engineering has boosted the power conversion efficiency (PCE) of single-junction PSCs over 17%. As an emerging technology, it is still a challenge to prepare solution-processed flexible electrodes for attractive flexible PSCs. Poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) is one of the most promising candidates for electrodes due to its high conductivity (>4000 S/cm), excellent transmittance (>90%), intrinsically high work function (WF > 5.0 eV), and aqueous solution processability. To date, a great number of single-junction PSCs based on PEDOT:PSS electrodes have realized a PCE over 12%. In this review, we introduce the current research on the conductive complex PEDOT:PSS as well as trace the development of PEDOT:PSS used in electrodes for high performance PSCs and perovskite solar cells. We also discuss and comment on the aspects of conductivity, transmittance, work-function adjustment, film preparing methods, and device fabrications. A perspective on the challenges and future directions in this field is be offered finally.

Cold Crystallization Temperature Correlated Phase Separation, Performance, and Stability of Polymer Solar Cells

Summary Fabrication of non-fullerene (NF)-based polymer solar cells (PSCs) has been an arduous task involving various approaches to optimize the morphology of blend film for superior performance. In this work, unique exothermic peaks can be observed in differential scanning calorimetry first heating scan of the blend films, which are assigned to the cold crystallization temperature (TCC) of NF acceptors when blended with different degree of crystallinity polymers, and TCC contains the phase information at quenched stage of the film development. A linear correlation between the phase separation parameters and TCC was established, which helps to select the appropriate donor for a specific acceptor. Utilizing multiple polymer-NF blend systems, we report an expectation TCC value between 210°C and 230°C, which would promise balanced domain size, purity, and consequentially superior performance. Further investigation revealed that TCC can also be used to evaluate the thermal stability.

A 9.16% Power Conversion Efficiency Organic Solar Cell with a Porphyrin Conjugated Polymer Using a Nonfullerene Acceptor.

A new low-molecular-weight porphyrin-based polymer, PPPyDPP, with pyridine-capped diketopyrrolopyrrole (DPP) has been synthesized, and its optical and electrochemical properties were investigated. The polymer is prepared with a low content of homocoupling units and gives a widely spread absorption from 400 to 900 nm with a narrow optical band gap of 1.46 eV. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels are respectively located at -5.27 and -3.78 eV, respectively. PPPyDPP was used as the electron donor, whereas [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) and bis(rhodanine)indolo-[3,2-b]-carbazole (ICzRd2), a nonfullerene small molecule, were used as acceptors for the fabrication of solution-processed bulk heterojunction polymer solar cells. Overall power conversion efficiencies (PCEs) of 7.31 and 9.16% (record high for porphyrin-containing polymers) were obtained for PC71BM and ICzRd2, respectively. A high Voc of 1.01 V and a low Eloss of 0.45 eV may explain this new record.

Small molecule acceptors with indacenodithiophene–benzodithiophene–indacenodithiophene as donating cores for solution-processed non-fullerene solar cells

Abstract Two acceptor-donor1-donor2-donor1-acceptor (A-D1-D2-D1-A)-type narrow bandgap small molecules BDT(IDT-IC)2 and BDT(IDT-IC-2F)2 with indacenodithiophene–benzodithiophene-indacenodithiophene (BDT-(IDT)2) as donating cores and 2-(3-oxo-2,3-dihydroinden-1-ylidene) malononitrile (IC) or 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-ylidene) malononitrile (2FIC) as end groups, have been synthesized and investigated as non-fullerene acceptors in solution-processed polymer solar cells (PSCs). The optical bandgaps of BDT(IDT-IC)2 and BDT(IDT-IC-2F)2 are 1.59 eV and 1.54 eV, respectively. Using PBDB-T as donor, the power conversion efficiencies (PCEs) of 4.98% and 6.21% are achieved by PSCs based on BDT(IDT-IC)2 and BDT(IDT-IC-2F)2, respectively.

Synthesis and Characterization of Benzodithiophene-4,8-Dione-Based Copolymers for Polymer Solar Cells.

A novel series of benzodithiophene-4,8-dione (BDD)-based copolymers, poly[(4,4,9,9-tetrakis(4-hexylphenyl)-4,9-dihydro-s-indacenodithiophene-2,7-diyl)-alt-(1,3-bis(2-ethylhexyl)-5,7-di(thiophene2-yl)benzodithiophene-4,8-dione)] (P1) and poly[(5,5,11,11-tetrakis(4-hexylphenyl)dithieno[2,3-d: 2',3'-d']-s-indacenodithiophene-3,9-diyl)-alt-(1,3-bis(2-ethylhexyl)-5,7-di(thiophene-2-yl)benzodithiophene-4,8-dione)] (P2), which have the same acceptor moiety but different donor segments, have been designed and synthesized for use as donor materials in solution-processable polymer solar cells (PSCs). The optical and photovoltaic properties of the copolymers were investigated. The band gaps of the copolymers were in the range 1.91-1.92 eV. Under optimized conditions, the BDD-based polymers showed power conversion efficiencies (PCEs) for the PSCs in the range 2.52-2.92% under AM 1.5 illumination (100 mW/cm2). Among the copolymers, P1, which contained an indacenodithiophene donor unit, showed a power conversion efficiency of 2.92% with a short circuit current of 7.30 mA/cm2, open circuit voltage of 0.92 V, and a fill factor of 0.43, under AM 1.5 illumination (100 mW/cm2).

Chemical optimization of benzo-dithiophene and benzo-[2,1,3]thiadiazole copolymers for the high performance, green-solvent-processed polymer solar cells

In this work, we demonstrate the chemical optimization of benzo[1,2-b:4,5-b′]dithiophene (BDT)-5,6-difluorobenzo-[2,1,3]thiadiazole (FBT) D-A alternating copolymer for obtaining the efficient polymeric donors for the environment-friendly solution processed polymer solar cells (PSCs). Three polymers PBTF, PBTTF-C6 and PBTTF-H, in which one or two alky thiophene units are inserted into the backbone of BDT-FBT alternating copolymer, present much different performances either in the PSCs processed from halogenated solvent and additive or in the PSCs processed from non-halogenated solvent and additive. With an alky thiophene and a bare thiophene as the spacer, PBTTF-H performs best among the three. Especially when the devices processed from 1,2,4-trimethylbenzene and diphenyl ether, in which the highest PCE of 6.80% is achieved with a VOC of 0.77 V, a JSC of 13.67 mA cm−2 and a FF of 64.2%. We think these results will cast light on developing new polymeric donors of the green-solvent-processed PSCs.

Quadruple Junction Polymer Solar Cells with Four Complementary Absorber Layers.

A monolithic two-terminal solution-processed quadruple junction polymer solar cell in an n-i-p (inverted) configuration with four complementary polymer:fullerene active bulk-heterojunction layers is presented. The subcells possess different optical bandgaps ranging from 1.90 to 1.13 eV. Optical modeling using the transfer matrix formalism enables prediction of the fraction of absorbed photons from sunlight in each subcell and determine the optimal combination of layer thicknesses. The quadruple junction cell features an open-circuit voltage of 2.45 V and has a power conversion efficiency of 7.6%, only slightly less than the modeled value of 8.2%. The external quantum efficiency spectrum, determined with appropriate light and voltage bias conditions, exhibits in general an excellent agreement with modeled spectrum. The device performance is presently limited by bimolecular recombination, which prevents using thick photoactive layers that could absorb light more efficiently.

Closely packed, low reorganization energy π-extended postfullerene acceptors for efficient polymer solar cells

New organic semiconductors are essential for developing inexpensive, high-efficiency, solution-processable polymer solar cells (PSCs). PSC photoactive layers are typically fabricated by film-casting a donor polymer and a fullerene acceptor blend, with ensuing solvent evaporation and phase separation creating discrete conduits for photogenerated holes and electrons. Until recently, n-type fullerene acceptors dominated the PSC literature; however, indacenodithienothiophene (IDTT)-based acceptors have recently enabled remarkable PSC performance metrics, for reasons that are not entirely obvious. We report two isomeric IDTT-based acceptors 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-benz-(5, 6)indanone))-5,5,11,11-tetrakis(4-nonylphenyl)-dithieno[2,3-d:2',3'-d']-s-indaceno[1,2-b:5,6-b']di-thiophene (ITN-C9) and 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-benz(6,7)indanone))-5,5,11,11-tetrakis(4-nonylphenyl)-dithieno[2,3-d:2',3'-d']-s-indaceno[1,2-b:5,6-b']dithiophene (ITzN-C9) that shed light on the exceptional IDTT properties vis-à-vis fullerenes. The neat acceptors and blends with fluoropolymer donor poly{[4,8-bis[5-(2- ethylhexyl)-4-fluoro-2-thienyl]benzo[1,2-b:4,5-b']dithiophene2,6-diyl]-alt-[2,5-thiophenediyl[5,7-bis(2-ethylhexyl)-4,8-dioxo4H,8H-benzo[1,2-c:4,5-c']dithiophene-1,3-diyl]]} (PBDB-TF) are investigated by optical spectroscopy, cyclic voltammetry, thermogravimetric analysis, differential scanning calorimetry, single-crystal X-ray diffraction, photovoltaic response, space-charge-limited current transport, atomic force microscopy, grazing incidence wide-angle X-ray scattering, and density functional theory-level quantum chemical analysis. The data reveal that ITN-C9 and ITzN-C9 organize such that the lowest unoccupied molecular orbital-rich end groups have intermolecular π-π distances as close as 3.31(1) Å, with electronic coupling integrals as large as 38 meV, and internal reorganization energies as small as 0.133 eV, comparable to or superior to those in fullerenes. ITN-C9 and ITzN-C9 have broad solar-relevant optical absorption, and, when blended with PBDB-TF, afford devices with power conversion efficiencies near 10%. Performance differences between ITN-C9 and ITzN-C9 are understandable in terms of molecular and electronic structure distinctions via the influences on molecular packing and orientation with respect to the electrode.

Achieving over 9.8% Efficiency in Nonfullerene Polymer Solar Cells by Environmentally Friendly Solvent Processing

Nowadays, most of the solution-processed high-efficiency polymer solar cell (PSC) devices are fabricated by halogenated solvents (such as chlorobenzene, 1,2-dichlorobenzene, chloroform, etc.) which are harmful to people and the environment. Therefore, it is essential to develop high-efficiency PSC devices processed by environmentally friendly solvent processing for their industrialization. In this regard, we report a new alkylthio chain-based conjugated polymer PBDB-TS as donor material for environmentally friendly solvent-processed PSCs. PBDB-TS possesses a low-lying HOMO energy level at -5.42 eV and a good solubility in toluene and o-xylene. By using o-xylene and 1% N-methylpyrrolidone as processing solvent, following by the thermal annealing treatment for PBDB-TS:ITIC blend films, well-developed morphological features, and balanced charge transport properties are observed, leading to a high power conversion efficiency (PCE) of 9.85%, higher than that of the device cast from halogenated solvent (PCE = 9.65%). The results suggest that PBDB-TS is an attractive donor material for nonhalogen solvents-processing PSCs.

Polymer solar cells based low bandgap A1-D-A2-D terpolymer based on fluorinated thiadiazoloquinoxaline and benzothiadiazole acceptors with energy loss less than 0.5 eV

We synthesized an ultra low bandgap terpolymer denoted as P containing fluorinated-fluorene attached thiadiazoloquinoxaline and benzothiadiazole acceptors and thiophene as donor in its backbone and investigated its optical and electrochemical properties. This terpolymer is used for as donor along with PC71BM as electron acceptor in solution processed polymer solar cells (PSCs). The P showed a shows strong absorption band from 650 nm to 1100 nm with an optical bandgap of 1.12 eV and highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of −5.25 eV and −3.87 eV, respectively. After the optimization of P to PC71BM weight ratio, the optimized weight ratio 1:2 in chlorobenzene (CB) solution, the PSC showed overall power conversion efficiency of 4.10% (Jsc of 10.96 mA/cm2, Voc of 0.68 V and FF of 0.55). After the solvent additive (3 v% DIO) followed by subsequent thermal annealing (SA-TA) the PCE has been increased up to 7.54% with Jsc of 16.12 mA/cm2, Voc of 0.65 V and FF of 0.72. The increase in the PCE is related with the enhancement in the both Jsc and FF, attributed optimized nanoscale morphology of the active layer for both efficient exciton dissociation and charge transport towards the electrodes and balanced charge transport in the device, induced by the TSA treatment of the active layer. This is the highest PCE of PSCs with an energy loss about 0.47 eV with the low bandgap of 1.12 eV.

An easily prepared Ag8GeS6 nanocrystal and its role on the performance enhancement of polymer solar cells

Novel Ag8GeS6 nanocrystal materials (AGS NCs) have recently earned affectionate attention due to its bulk band-gap of 1.4 eV, which makes it ideal as a broad-spectrum absorber material for both semiconductor photocatalyst and photovoltaic devices. In this paper, we investigated the role of AGS NCs as molecular dopant on solution-processed polymer solar cells (PSCs). Argyrodite AGS NCs was prepared via a colloidal synthesis process using simple inorganic compounds as precursors. Incorporating AGS NCs into PSCs leads to not only improved light absorption of active layer but also increased phase separation of donor and acceptor. Moreover, the doping effect of AGS NCs was also confirmed by nanoscale morphology and photocurrent generation mechanism analysis, revealing that AGS NCs could serve as both exciton dissociation centers and charge transfer medium. This study shows that employment of AGS NCs is a facile way to improve the electrical and optical properties of organic photovoltaic devices.

Roll-to-roll micro-gravure printed large-area zinc oxide thin film as the electron transport layer for solution-processed polymer solar cells

Large-scale, roll-to-roll (R2R) micro-gravure printing process was developed to deposit the electron transport layer (ETL) using low-temperature, solution-processable zinc oxide (ZnO) nanoparticle ink on flexible substrate for fabricating inverted organic solar cells (OSCs). The properties of micro-gravure R2R printed ZnO thin film was optimized via using web tension, substrate pre-treatment and printing speed, leading to high-quality and thickness controllable ZnO thin films. The inverted OSCs using R2R micro-gravure printed ZnO thin film as the ETL showed performance parameters comparable to those of spin-coated ZnO thin film ETL on the flexible substrate in both P3HT:PCBM and PTB7-Th:PC71BM based devices. The research demonstrated that the potentially commercial large-scale, R2R micro-gravure printing process could be used to produce high-quality ZnO thin film with controllable thickness for efficient inverted OSCs, which would accelerate the development of fully R2R micro-gravure printing OSCs and their commercialization.

High-Performance Solution-Processed Single-Junction Polymer Solar Cell Achievable by Post-Treatment of PEDOT:PSS Layer with Water-Containing Methanol.

PSS (poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)) is widely used as the hole-transporting layer for fabrication of new-generation solar cells. Herein, we utilize water-containing methanol to post-treat the PEDOT:PSS surface, by which the insulating PSS component is partially washed out with the PEDOT-to-PSS weight ratio increasing from 1:6.79 to 1:2.93. As a result, the surface becomes more covered with the electrically conductive PEDOT nanodomains, and again the mean current of the conductive nanodomains increases slightly from 6.68 to 7.28 pA, as demonstrated with conductive atomic force microscopy images. The electrical conductivity of the bulk PEDOT:PSS layer increases from 5.51 × 10-4 to 4.04 × 10-2 S/cm. The improvement in the surface conductivity allows for more efficient collection of mobile holes with a bit higher value of the hole mobility (5.56 vs 6.78 × 10-4 cm2 V-1 s-1). The solution-processed single-junction polymer solar cell fabricated on the treated PEDOT:PSS surface shows a higher mean short-circuit current-density (14.46 vs 16.48 mA cm-2) and, hence, a higher mean power conversion efficiency (8.23% vs 9.28%) than that on the untreated surface, as calculated from over 200 cells.