Showing papers by "Alex K.-Y. Jen published in 2012"
TL;DR: In this paper, the authors provide an overview on the recent development of solution processed organic, inorganic, and hybrid interfacial materials for bulk-heterojunction polymer solar cells.
Abstract: This article provides an overview on the recent development of solution processed organic, inorganic, and hybrid interfacial materials for bulk-heterojunction polymer solar cells. The introduction of proper interfacial materials to optimize the electronic and electrical properties between the interfaces of the light-harvesting active layer and the charge-collecting electrode has become an important criterion to improve the performance of polymer solar cells. The electronic processes at these interfaces play a critical role in determining the efficiency for photon-to-electricity conversion. An ideal interface requires the formation of Ohmic contact with minimum resistance and high charge selectivity to prevent charge carriers from reaching the opposite electrodes. For long-term stability of polymer solar cells, interfaces with matched surface energy are required to prevent interfacial dewetting and delamination. Several classes of interfacial materials including inorganic metal oxides, crosslinkable charge-transporting materials, conjugated polymer electrolytes, self-assembled functional molecules, and graphene-based materials are highlighted and the integration of these interfacial materials with new low bandgap polymers and fullerene derivatives as active materials in different device architectures is also discussed.
995 citations
TL;DR: In this article, the development of functional fullerenes as acceptors, electron selective layers, and morphology stabilizers for bulk heterojunction polymer solar cells is reviewed, and a wide variety of newly developed fullerene-derived molecules have appeared in the past few years and started to show very encouraging photovoltaic performance when they were blended with low bandgap conjugated polymers.
Abstract: Tremendous progress has been made on the design and processing of new active and interfacial materials to enable organic photovoltaics to achieve high power conversion efficiencies of >10%. In this Feature Article the development of functional fullerenes as (1) acceptors, (2) electron selective layers, and (3) morphology stabilizers for bulk heterojunction polymer solar cells is reviewed. In addition to the standard PCBM based acceptors, a wide variety of newly developed fullerene-derived molecules have appeared in the past few years and started to show very encouraging photovoltaic performance when they were blended with low bandgap conjugated polymers. New fullerene derivatives with proper molecular design can also serve as electron selective interfacial materials and morphology stabilizers for the bulk heterojunction layer, which are essential to improve the interfacial property and long term stability of polymer solar cells. Although there still are many challenges ahead before practical polymer solar cells will arrive in the market place, the research in functional fullerenes deserves to have more attention in order to expedite this development process.
450 citations
TL;DR: A novel ladder-type donor (IDTT) is developed by substituting the two outward thiophenes of the IDT donor with two thieno[3,2-b]thiophene, which improves electron delocalization along the polymer backbone and charge mobility.
Abstract: A novel ladder-type donor (IDTT) is developed by substituting the two outward thiophenes of the IDT donor with two thieno[3,2-b]thiophenes. The polymer derived from this donor possesses longer effective conjugation and better planarity, which improves electron delocalization along the polymer backbone and charge mobility. The polymer solar cell device using PIDTT-DFBT shows a high power conversion efficiency of 7.03% with a large open-circuit voltage of 0.95 V without using any additives or post-solvent/thermal annealing processes.
338 citations
TL;DR: Inverted semi-transparent organic photovoltaic (OPV) cells with very high device performance, tunable transparency, and extraordinary transparency color perception and rendering properties have been demonstrated for power-generating window applications for buildings and automotives as discussed by the authors.
Abstract: Inverted semi-transparent organic photovoltaic (OPV) cells with very high device performance, tunable transparency, and extraordinary transparency color perception and rendering properties have been demonstrated for power-generating window applications for buildings and automotives.
326 citations
190 citations
TL;DR: A partially fluorinated low bandgap polymer, poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta [2,1-b;3,4b′]dithiophene)-alt-4,7-(5-fluoro-[2, 1,3]-benzothiadiazole] (PCPDTFBT) was synthesized through a microwave-assisted Stille polymerization as mentioned in this paper.
Abstract: A partially fluorinated low bandgap polymer, poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta [2,1-b;3,4-b′]dithiophene)-alt-4,7-(5-fluoro-[2,1,3]-benzothiadiazole)] (PCPDTFBT) was synthesized through a microwave-assisted Stille polymerization. It was found that PCPDTFBT has better π–π stacking in solution than its nonfluorinated analogue, poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b′]dithiophene)-alt-4,7-([2,1,3]-benzothiadiazole)] (PCPDTBT), resulting in 2 times higher hole mobility. Power conversion efficiency (PCE) of the device using PCPDTFBT/PC71BM as active layer (5.51%) is much higher than the device using PCPDTBT/PC71BM (2.75%) that was fabricated under the same condition without using any solvent additive to modify the morphology. The significantly enhanced PCE is the result of improved open circuit voltage and short circuit current coming from the lower lying HOMO energy level and the appropriate morphology of PCPDTFBT. In addition, the device with PCPDTFBT/PC71BM could also be proces...
180 citations
TL;DR: In this article, two methanol-soluble fullerene surfactants have been developed as interfacial layers for cathodes in polymer solar cells, which facilitate the tuning of cathode work function and extraction of electrons that significantly enhance open-circuit voltage and photocurrent generation.
Abstract: Two methanol-soluble fullerene surfactants have been developed as interfacial layers for cathodes in polymer solar cells. These surfactants facilitate the tuning of cathode work function and extraction of electrons that significantly enhance open-circuit voltage and photocurrent generation. The performance of bulk heterojunction solar cells based on using these surfactant-modified cathodes improved significantly to afford high power conversion efficiencies (as high as 6.63% for a Ag cathode).
162 citations
TL;DR: The combination of excellent dielectric and interfacial properties results in high-performance OFETs with low-subthreshold slopes down to 75 mV dec(-1), high I(on)/I(off) ratios of 10(5)-10(7), contact resistance down to 700 Ω cm, and general applicability to solution-processed and vacuum-deposited n-type and p-type organic and polymer semiconductors.
Abstract: Insulating and semiconducting molecular phosphonic acid (PA) self-assembled monolayers (SAMs) have been developed for applications in organic field-effect transistors (OFETs) for low-power, low-cost flexible electronics. Multifunctional SAMs on ultrathin metal oxides, such as hafnium oxide and aluminum oxide, are shown to enable (1) low-voltage (sub 2 V) OFETs through dielectric and interface engineering on rigid and plastic substrates, (2) simultaneous one-component modification of source–drain and dielectric surfaces in bottom-contact OFETs, and (3) SAM-FETs based on molecular monolayer semiconductors. The combination of excellent dielectric and interfacial properties results in high-performance OFETs with low-subthreshold slopes down to 75 mV dec−1, high Ion/Ioff ratios of 105–107, contact resistance down to 700 Ω cm, charge carrier mobilities of 0.1–4.6 cm2 V−1 s−1, and general applicability to solution-processed and vacuum-deposited n-type and p-type organic and polymer semiconductors.
139 citations
TL;DR: ITO-free polymer solar cells with efficiencies as high as 6.6% and 5.8% are fabricated on glass and polyethylene naphthalate by using TeO(2) to enhance the in-coupling of light in an Ag-Ag microcavity.
Abstract: ITO-free polymer solar cells with efficiencies as high as 6.6% and 5.8% are fabricated on glass and polyethylene naphthalate (PEN) by using TeO(2) to enhance the in-coupling of light in an Ag-Ag microcavity. These cells exhibit higher performance, selective microcavity resonance as a function of the thickness of TeO(2) , and better bending stability than flexible devices made with ITO.
129 citations
TL;DR: In this article, 2% 1-methylnaphthalene (Me-naph) was used as a processing additive to toluene to solve the solubility problem of PC71BM.
81 citations
TL;DR: A series of highly polarizable chromophores 1−3 have been synthesized based on three different types of electron donors, including diethylaminophenyl, tetrahydroquinolinyl and julolidinyl groups respectively, with the same isophorone-derived tetraene bridges and strong CF3-TCF acceptors as mentioned in this paper.
Abstract: A series of highly polarizable chromophores 1–3 has been synthesized based on three different types of electron donors, including diethylaminophenyl, tetrahydroquinolinyl and julolidinyl groups respectively, with the same isophorone-derived tetraene bridges and strong CF3–TCF acceptors. The progressively increased electron-donating strength for these chromophores allows for the fine-tuning of their molecular ground-state polarization, being very close to optimal for very large hyperpolarizability (β), as a function of the local dielectric environment and poling-induced acentric ordering. The solvatochromic study and DFT calculations suggested that more dipolar chromophores 2 and 3 with stronger donating groups can be polarized quite close to the cyanine limit, or even beyond that into the zwitterionic regime in the most polar solvents to give the inverted solvatochromism and diminished β values. This is in stark contrast to the polyene-like characteristic of 1 with the diethylaminophenyl donor in all the tested solvents. Most intriguingly, the electric field poling has induced significant changes in the position, intensity and shape of the chromophoric charge-transfer absorption band in their poled thin films. It is thus indicated that the nontrivial intermolecular interaction in solid state can vary the reaction field that acts on the chromophores in poled and depoled films, and significantly affect their achievable electro-optic (EO) activities. As a result, the guest–host polymers containing 10 wt% of chromophores in PMMA showed EO coefficients of ∼80 pm V−1 for 1/PMMA and 2/PMMA, while dramatically dropping to 20 pm V−1 for 3/PMMA. These systematic analyses led to the rational design of a new guest–host EO polymer incorporating 35 wt% of a spatially modified chromophore AJLZ55, which gave ultrahigh EO coefficients of 218 pm V−1 at 1.31 μm.
TL;DR: In this paper, a detailed model study has shown that thin film morphology and bulk-heterojunction solar cell performance can be significantly improved by systematic tuning of the surface energy of the conjugated donor polymer through side-chain functionalization.
Abstract: A detailed model study has shown that thin film morphology and bulk-heterojunction solar cell performance can be significantly improved by systematic tuning of the surface energy of the conjugated donor polymer through side-chain functionalization. Thiophene-flanked diketopyrrolopyrrole (DPP) moieties with different contents of cyanohexane side chains were incorporated into three low band-gap conjugated copolymers (PIDTDPP1, PIDTDPP2 and PIDTDPP3) consisting of indacenodithiophene (IDT) donors and DPP acceptors. The resulting polymers possessed good solubility in common organic solvents and showed similar energy levels, bandgaps, and hole mobilities. However, the introduction of cyano groups onto the terminal of side-chains significantly changed their surface energy. Topographical images obtained from atomic force microscopy (AFM) proved that a better matched surface energy between polymer and PC71BM had led to enhanced miscibility, which resulted in better BHJ film morphology. Consistent with the surface energy enhancement, the performance of BHJ photovoltaic devices increased from 0.97% for PIDTDPP1, to 2.16% for PIDTDPP2 then to 3.67% for PIDTDPP3. These results clearly reveal that tuning surface energy is an effective way to improve the morphology of the BHJ active layer and efficiency of the photovoltaic device.
TL;DR: Recently, a hybrid type 1T–1R and 1D-1R device architecture is reported, which is composed of a hybrid ONVM device with Si-based transistors or Si schottky diodes.
Abstract: ONVM is one emerging technology that has been explored as the next generation data storage media. In literature, there are numerous reports regarding the switching mechanisms for ONVM devices, [ 15–18 ] as well as the development of new organic materials [ 15 , 18–21 ] and device architectures [ 22–27 ] for ONVM applications. Research on novel device architectures can potentially generate more reliable organic memory devices with higher density and improved performance, while simultaneously mitigating misreading (cross-talk) issues. For these reasons, organic one diode-one resistor (1D–1R) type devices have been demonstrated. [ 23,24 ] However, these devices exhibit irreversible switching behavior and are nonpatternable, which strongly limits their application in systems that require both an array architecture and rewritable memory capability. Recently, we have reported a hybrid type 1T–1R and 1D–1R device architecture, which is composed of a hybrid ONVM device with Si-based transistors or Si schottky diodes. [ 25,26 ]
TL;DR: This work represents the first time that polymer thickness has been controlled in a surface initiated K CTP reaction, highlighting the utility of KCTP in achieving controlled polymerizations.
Abstract: Poly(3-methylthiophene) (P3MT) was synthesized directly from indium tin oxide (ITO) electrodes modified with a phosphonic acid initiator, using Kumada catalyst transfer polymerization (KCTP). This work represents the first time that polymer thickness has been controlled in a surface initiated KCTP reaction, highlighting the utility of KCTP in achieving controlled polymerizations. Polymer film thicknesses were regulated by the variation of the solution monomer concentration and ranged from 30 to 265 nm. Electrochemical oxidative doping of these films was used to manipulate their near surface composition and effective work function. Doped states of the P3MT film are maintained even after the sample is removed from solution and potential control confirming the robustness of the films. Such materials with controllable thicknesses and electronic properties have the potential to be useful as interlayer materials for organic electronic applications.
TL;DR: The results suggest that kinetics, as opposed to thermodynamics, can dominate recombination via triplet excitons in these blends and that optimization of charge separation and kinetic suppression of charge recombination may be fruitful paths for the next generation of panchromatic organic solar cell materials with high V(OC) and J(SC).
Abstract: We study charge recombination via triplet excited states in donor/acceptor organic solar cells and find that, contrary to intuition, high internal quantum efficiency (IQE) can be obtained in polymer/fullerene blend devices even when the polymer triplet state is significantly lower in energy than the intermolecular charge transfer (CT) state. Our model donor system comprises the copolymer PIDT-PhanQ: poly(indacenodithiophene-co-phenanthro[9,10-b]quinoxaline), which when blended with phenyl-C71-butyric acid methyl ester (PC71BM) is capable of achieving power conversion efficiencies of 6.0% and IQE ≈ 90%, despite the fact that the polymer triplet state lies 300 meV below the interfacial CT state. However, as we push the open circuit voltage (VOC) higher by tailoring the fullerene reduction potential, we observe signatures of a new recombination loss process near VOC = 1.0 V that we do not observe for PCBM-based devices. Using photoinduced absorption and photoluminescence spectroscopy, we show that a new reco...
TL;DR: In this article, a detailed study of solution-processed, inverted-structure PSCs based on the blends of a low bandgap polymer, poly(indacenodithiophene-co-phananthrene-quinoxaline) (PIDT-PhanQ) and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as the bulk heterojunction (BHJ) layer is carried out.
Abstract: Although high power conversion efficiencies (PCE) have already been demonstrated in conventional structure polymer solar cells (PSCs), the development of high performance inverted structure polymer solar cells is still lagging behind despite their demonstrated superior stability and feasibility for roll-to-roll processing. To address this challenge, a detailed study of solution-processed, inverted-structure PSCs based on the blends of a low bandgap polymer, poly(indacenodithiophene-co-phananthrene-quinoxaline) (PIDT-PhanQ) and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as the bulk heterojunction (BHJ) layer is carried out. Comprehensive characterization and optical modeling of the resulting devices is performed to understand the effect of device geometry on photovoltaic performance. Excellent device performance can be achieved by optimizing the optical field distribution and spatial profiles of excitons generation within the active layer in different device configurations. In the inverted structure, because the peak of the excitons generation is located farther away from the electron-collecting electrode, a higher blending ratio of fullerene is required to provide higher electron mobility in the BHJ for achieving good device performance.
TL;DR: In this paper, a spectroscopic and device-based investigation is presented, which leads to a new optimization route where by functionalization of the TiO 2 surface with a molecular electron acceptor promotes photoinduced electron transfer from a low-band gap polymer(poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[ 2,1-b;3,4b0]dithiophene)-alt-4,7-(2,1,3-benzothiadia-zole)] (PC
Abstract: Hybrid solar cells based on light absorbing semiconducting polymers infi ltrated in nanocrystalline TiO 2 electrodes, have emerged as an attractive concept, combining benefi ts of both low material and processing costs with well controlled nano-scale morphology. However, after over ten years of research effort, power conversion effi ciencies remain around 0.5%. Here, a spectroscopic and device based investigation is presented, which leads to a new optimization route where by functionalization of the TiO 2 surface with a molecular electron acceptor promotes photoinduced electron transfer from a low-band gap polymer(poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4b0]dithiophene)-alt-4,7-(2,1,3-benzothiadia-zole)] (PCPDTBT) to the metal oxide. This boosts the infrared response and the power conversion effi ciency to over 1%. As a further step, by “co-functionalizing” the TiO 2 surface with the electron acceptor and an organic dye-sensitizer, panchromatic spectral photoresponse is achieved in the visible to near-IR region. This novel architecture at the heterojunction opens new material design possibilities and represents an exciting route forward for hybrid photovoltaics.
TL;DR: In this paper, an all-dielectric electro-optic (EO) polymer/TiO2 multilayer slot waveguide modulator with low optical insertion loss for high-speed operations is presented.
Abstract: We report an all-dielectric electro-optic (EO) polymer/TiO2 multilayer slot waveguide modulator with low optical insertion loss for high-speed operations. The EO polymer is sandwiched between thin TiO2 slot waveguide films to improve mode confinement in the EO polymer. The structure increased the mode confinement in the TiO2 and EO polymer slot layers and reduced the electrode distance between the Au electrodes without introducing optical loss from the metal electrodes. The half-wave voltage of the modulator was 6.5 V for a 5-mm-long electrode at a wavelength of 1550 nm. The half-wave voltage and length product was 3.25 V·cm.
TL;DR: In this paper, a series of fullerene acceptors have been selected for the systematic study of their electron-transporting properties on a standardized field effect transistor (FET) platform.
Abstract: A series of fullerene acceptors have been selected for the systematic study of their electron-transporting properties on a standardized field-effect transistor (FET) platform It was found that small structural alternations, functional patterns, and number of addends on fullerene derivatives strongly affect their mobilities The measured charge mobilities correlate well with structural features of these materials and provide useful insights into designing better fullerene-based semiconductors for organic electronics
TL;DR: A novel position-resolved resonance trimming strategy for silicon ring resonators covered with a chromophore-doped guest host polymer cladding that can be used to trim the resonance frequency of the ring resonator.
Abstract: We demonstrate a novel position-resolved resonance trimming strategy for silicon ring resonators. Ring resonators are covered with a chromophore-doped guest host polymer cladding. Illumination of the polymer cladding with high-energy electrons causes a bleaching of the chromophore molecules. Bleaching of the chromophores induces a reduction of the polymer refractive index, which can be used to trim the resonance frequency of the ring resonators. A maximum refractive index change of 0.06 and a TM polarization resonance shift of 16.4 nm have been measured. A Q factor of 20,000 before bleaching remains unaltered after the electron beam exposure process.
TL;DR: A series of highly efficient and thermally stable electro-optic polymers have been developed by poling and crosslinking in situ the blend of high glass-transition temperature (Tg) anthracene-containing polymers and acrylate-functionalized dendritic nonlinear optical (NLO) chromophores.
Abstract: A series of highly efficient and thermally stable electro-optic (EO) polymers have been developed by poling and crosslinking in situ the blend of high glass-transition temperature (Tg) anthracene-containing polymers and acrylate-functionalized dendritic nonlinear optical (NLO) chromophores. By molecular engineering of the shape, nonlinearity, Tg, and crosslinking moieties of the chromophores and polymers, the resultant materials showed significantly enhanced EO activities (r33 values as high as 126 pm V−1 at 1310 nm) and alignment stability (up to 200 °C). Poling efficiency of these EO polymers could be improved by 35–50% by using simplified lattice hardening and poling protocols. The combined good processability, large EO activities, and high temperature stability endow these materials as promising candidates for device exploration in the CMOS-based photonics.
TL;DR: The SAMs on curved surfaces exhibit dramatically lower regioselective photoreaction kinetics and efficiencies than those on atomically flat surfaces, attributed to the increased intermolecular distances and variable orientations on the curved surfaces.
Abstract: We identify and control the photoreaction paths of self-assembled monolayers (SAMs) of thiolate-linked anthracene phenylethynyl molecules on Au substrate surfaces, and study the effects of nanoscale morphology of substrates on regioselective photoreactions. Two types of morphologies, atomically flat and curved, are produced on Au surfaces by controlling substrate structure and metal deposition. We employ surface-enhanced Raman spectroscopy (SERS), combined with Raman mode analyses using density functional theory, to identify the different photoreaction paths and to track the photoreaction kinetics and efficiencies of molecules in monolayers. The SAMs on curved surfaces exhibit dramatically lower regioselective photoreaction kinetics and efficiencies than those on atomically flat surfaces. This result is attributed to the increased intermolecular distances and variable orientations on the curved surfaces. Better understanding of the morphological effects of substrates will enable control of nanoparticle fu...
TL;DR: The AIE properties of two trifluoromethyl substituted distyrylbenzene model compounds were compared and it was found that the fluorescence quantum efficiency of these molecules can be modulated by tuning their subtle solid-state intermolecular interactions.
TL;DR: Pyroelectric crystals are used as a conformal and detachable electric field source to efficiently pole electro-optic polymers in both parallel-plate (transverse) and in-plane (quasi-longitudinal) configurations.
Abstract: Pyroelectric crystals are used as a conformal and detachable electric field source to efficiently pole electro-optic (E-O) polymers in both parallel-plate (transverse) and in-plane (quasi-longitudinal) configurations. Large Pockels coefficients in poled thin films and high tunability of resonance wavelength shift in hybrid polymer silicon slot waveguide ring-resonator modulators have been achieved using this method.
TL;DR: In this article, a top-contact self-assembled monolayer field effect transistors (SAMFETs) were fabricated through both spin-coating and solution assembly of a semiconducting phosphonic acid-based molecule (BQT-PA), which exhibited dense surface coverage, bidentate binding, and tilt angles of ∼32° and ∼44° for the thiophene rings and alkyl chain, respectively.
TL;DR: Silicon nanowires are observed to behave as chemically modulated resistors and exhibit sensitive and fast electrical responses to vapors of common nitro explosives and their degradation by-products.
Abstract: Silicon nanowires are observed to behave as chemically modulated resistors and exhibit sensitive and fast electrical responses to vapors of common nitro explosives and their degradation by-products. The nanowires were prepared with a top-down nano-fabrication process on a silicon-on-insulator wafer. The surface of the silicon nanowires was modified by plasma treatments. Both hydrogen and oxygen plasma treatments can significantly improve the responses, and oxygen plasma changes the majority carrier from p- to n-type on the surface of silicon nanowire thin films. The sensitivity is found to increase when the cross-section of the nanowires decreases.
TL;DR: In this paper, a thin sol-gel derived titanium dioxide (TiO2) barrier layer was added to the high electric field poling process to improve the temporal stability of poled electro-optic polymers.
Abstract: Significantly enhanced temporal stability of poled electro-optic (E-O) polymers could be achieved by inserting a thin sol–gel derived titanium dioxide (TiO2) barrier layer in the high electric field poling process. The resulting poled film can retain >90% of its original r33 value (169 pm V−1 at 1310 nm) after being annealed at 85 °C for 500 h. This is significantly higher (∼30%) compared to that obtained without the TiO2 layer. This barrier approach is also applicable to a variety of dielectric polymers although the degree of enhancement varies. The enhanced temporal stability of E-O polymers is attributed to reduced charge injection/accumulation that improves the stability of screening charges for poled films.
TL;DR: In this paper, an efficient thermal cross-linking protocol for an azide-alkyne-based Huisgen 1,3-dipolar cycloaddition reaction was developed for making highly efficient electrooptic (EO) polymers.
Abstract: Efficient thermal cross-linking protocol for an azide–alkyne-based Huisgen 1,3-dipolar cycloaddition reaction has been developed for making highly efficient electrooptic (EO) polymers. The material...
TL;DR: In this article, a series of light harvesting conjugated polymers were designed and synthesized for polymer solar cells, which include an electron-rich thiophene-triphenylamine backbone and stable planar indacenodithiophene π-bridges terminated with tunable electron acceptors.
Abstract: A series of light-harvesting conjugated polymers were designed and synthesized for polymer solar cells. These newly designed polymers comprise an unusual two-dimensional conjugated structure with an electron-rich thiophene–triphenylamine backbone and stable planar indacenodithiophene π-bridges terminated with tunable electron acceptors. It was found that the electron-withdrawing strength of the acceptor could be used to manipulate the energy level of the lowest unoccupied molecular orbital and bandgap (as much as 0.3 eV), generating derivatives with complementary absorbance in the visible spectrum. This approach provides great flexibility in fine tuning the electronic and optical properties of the resultant polymers and facilitates the investigation of how these chemical modifications alter the subsequent photovoltaic properties of these materials. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012