Highly Bendable Large-Area Printed Bulk Heterojunction Film Prepared by the Self-Seeded Growth of Poly(3-hexylthiophene) Nanofibrils
TL;DR: In this paper, the authors applied a C&H process with a P3HT/PCBM m-xylene solution to generate P3H:PCBM nanofibril composite films and found that the hole transport was 2.6 times faster in the thickness direction and 6.5 times more conductive in the in-plane direction.
Abstract: Applying conventional printing technologies to fabricate large-area flexible bulk heterojunction (BHJ) solar cells is of great interest. Achieving this task requires (i) large tolerance of the maximum photoconversion efficiency (PCE) to the film thickness, (ii) fast hole transport in both the thickness and lateral directions of the BHJ layer, and (iii) improved stability against bending and heat. This paper demonstrates that a P3HT:PCBM BHJ layer made of long P3HT nanofibrils of almost 100% crystallinity can be an excellent approach to achieve large-area printed solar cells. We applied a cool-and-heat (C&H) process with a P3HT/PCBM m-xylene solution to generate P3HT:PCBM nanofibril composite films. We found that the hole transport of the nanofibril composite was 2.6 times faster in the thickness direction and 6.5 times more conductive in the in-plane direction compared with conventionally annealed composites. The fast hole transport in the thickness direction led to negligible dependence of the PCE on the...
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TL;DR: The proposed all-polymer solar cells have even better performance than the control polymer-fullerene devices with phenyl-C61-butyric acid methyl ester as the electron acceptor and exhibit dramatically enhanced strength and flexibility compared with polymer/PCBM devices.
Abstract: All-polymer solar cells have shown great potential as flexible and portable power generators. These devices should offer good mechanical endurance with high power-conversion efficiency for viability in commercial applications. In this work, we develop highly efficient and mechanically robust all-polymer solar cells that are based on the PBDTTTPD polymer donor and the P(NDI2HD-T) polymer acceptor. These systems exhibit high power-conversion efficiency of 6.64%. Also, the proposed all-polymer solar cells have even better performance than the control polymer-fullerene devices with phenyl-C61-butyric acid methyl ester (PCBM) as the electron acceptor (6.12%). More importantly, our all-polymer solar cells exhibit dramatically enhanced strength and flexibility compared with polymer/PCBM devices, with 60- and 470-fold improvements in elongation at break and toughness, respectively. The superior mechanical properties of all-polymer solar cells afford greater tolerance to severe deformations than conventional polymer-fullerene solar cells, making them much better candidates for applications in flexible and portable devices.
701 citations
TL;DR: In this paper, a series of poly(3-hexylthiophene)s (P3HTs) having a wide range of regioregularity (RR) from 64 to 98% were successfully produced.
Abstract: While the regioregularity (RR) of conjugated polymers is known to have a strong influence on their inherent properties, systematic study of the RR effect has been limited due to the lack of a synthetic methodology Herein, we successfully produced a series of poly(3-hexylthiophene)s (P3HTs) having a wide range of RR from 64 to 98% Incorporation of controlled amounts of head-to-head (H–H) coupled dimer in modified Grignard metathesis polymerization allows a facile tuning of the RR of the P3HTs with comparable molecular weight and low polydispersity Then, we investigated the effect of RR on structural, electrical, and mechanical properties of P3HTs in which a higher content of H–H regio-defects, namely lower RR, systematically lowered the degree of crystallinity Although high RR P3HT (98%) had higher charge carrier mobility (181 × 10–1 cm2 V–1 s–1), its strong crystallinity induced high brittleness and stiffness, resulting in device failure under a very small strain, as shown in tensile and bending test
187 citations
TL;DR: In this article, the chemico-physical and functional requirements for polymer nanofibers to be used in opto- and nanoelectronics, as well as recent advances in various promising device architectures, such as light emitting and photovoltaic devices, photodetectors, field effect transistors, piezo-and thermoelectric generators, and actuators, are summarized and discussed.
167 citations
TL;DR: A stretchable polymer channel layer for organic field-effect transistors is obtained by spin-coating a blend solution of polythiophene and rubber polymer with large stretchability of the polythyphene film layer.
Abstract: A stretchable polymer channel layer for organic field-effect transistors is obtained by spin-coating a blend solution of polythiophene and rubber polymer. A network of the polythiophene nanofibril bundles surface-embedded in the rubber matrix allows large stretchability of the polythiophene film layer.
151 citations
TL;DR: This work reviews recent major progress in the development of both electronic materials and devices toward the second skin and concludes with comments on future research directions of the field.
Abstract: Electronic second skin is touted as the next interface to expand applications of electronics for natural and seamless interactions with humans to enable smart health care, the Internet of Things, and even to amplify human sensory abilities. Thus, electronic materials are now being actively investigated to construct "second skin." Accordingly, electronic devices are desirable to have skin-like properties such as stretchability, self-healing ability, biocompatibility, and biodegradability. This work reviews recent major progress in the development of both electronic materials and devices toward the second skin. It is concluded with comments on future research directions of the field.
150 citations
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TL;DR: In this article, the authors report highly efficient polymer solar cells based on a bulk heterojunction of polymer poly(3-hexylthiophene) and methanofullerene.
Abstract: Converting solar energy into electricity provides a much-needed solution to the energy crisis the world is facing today. Polymer solar cells have shown potential to harness solar energy in a cost-effective way. Significant efforts are underway to improve their efficiency to the level of practical applications. Here, we report highly efficient polymer solar cells based on a bulk heterojunction of polymer poly(3-hexylthiophene) and methanofullerene. Controlling the active layer growth rate results in an increased hole mobility and balanced charge transport. Together with increased absorption in the active layer, this results in much-improved device performance, particularly in external quantum efficiency. The power-conversion efficiency of 4.4% achieved here is the highest published so far for polymer-based solar cells. The solution process involved ensures that the fabrication cost remains low and the processing is simple. The high efficiency achieved in this work brings these devices one step closer to commercialization.
5,431 citations
TL;DR: The future holds even greater promise for this technology, with an entirely new generation of ultralow-cost, lightweight and even flexible electronic devices in the offing, which will perform functions traditionally accomplished using much more expensive components based on conventional semiconductor materials such as silicon.
Abstract: Organic electronics are beginning to make significant inroads into the commercial world, and if the field continues to progress at its current, rapid pace, electronics based on organic thin-film materials will soon become a mainstay of our technological existence. Already products based on active thin-film organic devices are in the market place, most notably the displays of several mobile electronic appliances. Yet the future holds even greater promise for this technology, with an entirely new generation of ultralow-cost, lightweight and even flexible electronic devices in the offing, which will perform functions traditionally accomplished using much more expensive components based on conventional semiconductor materials such as silicon.
4,967 citations
TL;DR: In this article, the authors presented a review of several organic photovoltaics (OPV) technologies, including conjugated polymers with high-electron-affinity molecules like C60 (as in the bulk-heterojunction solar cell).
Abstract: There has been an intensive search for cost-effective photovoltaics since the development of the first solar cells in the 1950s. [1–3] Among all alternative technologies to silicon-based pn-junction solar cells, organic solar cells could lead the most significant cost reduction. [4] The field of organic photovoltaics (OPVs) comprises organic/inorganic nanostructures like dyesensitized solar cells, multilayers of small organic molecules, and phase-separated mixtures of organic materials (the bulkheterojunction solar cell). A review of several OPV technologies has been presented recently. [5] Light absorption in organic solar cells leads to the generation of excited, bound electron– hole pairs (often called excitons). To achieve substantial energy-conversion efficiencies, these excited electron–hole pairs need to be dissociated into free charge carriers with a high yield. Excitons can be dissociated at interfaces of materials with different electron affinities or by electric fields, or the dissociation can be trap or impurity assisted. Blending conjugated polymers with high-electron-affinity molecules like C60 (as in the bulk-heterojunction solar cell) has proven to be an efficient way for rapid exciton dissociation. Conjugated polymer–C60 interpenetrating networks exhibit ultrafast charge transfer (∼40 fs). [6,7] As there is no competing decay process of the optically excited electron–hole pair located on the polymer in this time regime, an optimized mixture with C60 converts absorbed photons to electrons with an efficiency close to 100%. [8] The associated bicontinuous interpenetrating network enables efficient collection of the separated charges at the electrodes. The bulk-heterojunction solar cell has attracted a lot of attention because of its potential to be a true low-cost photovoltaic technology. A simple coating or printing process would enable roll-to-roll manufacturing of flexible, low-weight PV modules, which should permit cost-efficient production and the development of products for new markets, e.g., in the field of portable electronics. One major obstacle for the commercialization of bulk-heterojunction solar cells is the relatively small device efficiencies that have been demonstrated up to now. [5] The best energy-conversion efficiencies published for small-area devices approach 5%. [9–11] A detailed analysis of state-of-the-art bulk-heterojunction solar cells [8] reveals that the efficiency is limited by the low opencircuit voltage (Voc) delivered by these devices under illumination. Typically, organic semiconductors with a bandgap of about 2 eV are applied as photoactive materials, but the observed open-circuit voltages are only in the range of 0.5–1 V. There has long been a controversy about the origin of the Voc in conjugated polymer–fullerene solar cells. Following the classical thin-film solar-cell concept, the metal–insulator–metal (MIM) model was applied to bulk-heterojunction devices. In the MIM picture, Voc is simply equal to the work-function difference of the two metal electrodes. The model had to be modified after the observation of the strong influence of the reduction potential of the fullerene on the open-circuit volt
4,816 citations
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TL;DR: In this article, a review summarizes recent progress in the development of polymer solar cells and provides a synopsis of major achievements in the field over the past few years, while potential future developments and the applications of this technology are also briefly discussed.
Abstract: This Review summarizes recent progress in the development of polymer solar cells. It covers the scientific origins and basic properties of polymer solar cell technology, material requirements and device operation mechanisms, while also providing a synopsis of major achievements in the field over the past few years. Potential future developments and the applications of this technology are also briefly discussed.
3,832 citations
TL;DR: When silvery films of the semiconducting polymer, trans polyacetylene, (CH)x, are exposed to chlorine, bromine, or iodine vapour, uptake of halogen occurs, and the conductivity increases markedly (over seven orders of magnitude in the case of iodine) to give silvery or silvery-black films, some of which have a remarkably high conductivity at room temperature.
Abstract: When silvery films of the semiconducting polymer, trans‘polyacetylene’, (CH)x, are exposed to chlorine, bromine, or iodine vapour, uptake of halogen occurs, and the conductivity increases markedly (over seven orders of magnitude in the case of iodine) to give, depending on the extent of halogenation, silvery or silvery-black films, some of which have a remarkably high conductivity at room temperature.
3,197 citations