Polymer solar cells

Polymer solar cells: Recent development and possible routes for improvement in the performance

Naphtho[2,3-c]thiophene-4,9-dione based polymers for efficient fullerene solar cells

Two dependent working mechanisms enables efficient ternary polymer solar cells with broad compositional tolerance

Although the rapid development of polymer solar cells (PSCs) has been achieved, it is still a great challenge to explore efficient ways for improving power conversion efficiency (PCE) of PSCs from materials and device engineering. Ternary strategy has been confirmed as an efficient way to improve PCE of PSCs by employing three kinds of materials. In this work, one polymer donor PM6, and two non-fullerene materials N3 and MF1 are selected to prepare ternary PSCs with layer-by-layer (LbL) or bulk-heterojunction (BHJ) structure. The LbL and BHJ-PSCs exhibit PCEs of 16.75% and 16.76% with 15wt% MF1 content in acceptors, corresponding to over 5% or 4% PCE improvement compared with N3-based binary PSCs with LbL or BHJ structure. The PCE improvement is mainly attributed to the fill factor enhancement from 73.29% to 76.95% for LbL-PSCs or from 74.13% to 77.51% for BHJ-PSCs by employing the ternary strategy. This work indicates that ternary strategy has great potential in preparing highly efficient LbL-PSCs via simultaneously optimizing molecular arrangement and the thickness of each layer.

Over 15% efficiency all-small-molecule organic solar cells enabled by a C-shaped small molecule donor with tailorable asymmetric backbone

Sensible design and synthesis of conjugating polymers is important to the development of polymer solar cells (PSCs). In this work, we synthesized and characterized two dioctylfluorene‐thiophene based conjugated copolymers, PFTDPP and PFTpBT, having different acceptor groups on the backbone. The photovoltaic properties of the copolymers blended with 6,6‐phenyl‐C61‐butyric acid methyl ester (PC61BM) as an electron acceptor were obtained. The PSC based on a conventional device configuration ITO/PEDOT:PSS/ Polymer:PC61BM/LiF/Al showed power conversion efficiencies (PCEs) of 2.42% and 3.02% for PFTDPP and PFTpBT, respectively. Methanol treatment was introduced to further optimize device performance, and the solvent treatment gave a dramatic increase in PCE. The best PCEs could reach 4.25% and 4.20% after methanol treatment under AM 1.5G illumination with an intensity of 100 mW cm−2 from a solar simulator. © 2015 Society of Chemical Industry

Synthesis and characterization of chiral nano-poly [(±)-2-sec-butyl aniline] and its application in the first chiral polymer solar cell

Rational design and synthesis of polymeric semiconductors is critical to the development of polymer solar cells (PSCs). In this work, a new series of benzodithiophene–difuranylbenzooxadiazole-based donor–acceptor co-polymers—namely, PBDT-DFBO, PBDTT-DFBO, and PBDTF-DFBO, with various side groups—have been developed for bulk-heterojunction PSCs. These side-group substituents provide the opportunity to tailor the opto-electrical properties of the polymers. In addition, we show that the reduction of the bandgap of polymers and the enhancement of charge mobility in the devices can be accomplished concurrently by substituting the alkylthienyl side group with its furan counterpart. In the preliminary investigation, one could obtain PSCs with a power conversion efficiency (PCE) of 2.1% for PBDT-DFBO with an alkoxyl side chain, 2.2% for PBDTT-DFBO with an alkylthienyl side group, and 3.0% for PBDTF-DFBO with an alkylfuranyl side group. Further optimizing the performance of the devices was conducted via a simple s...

With the rapid development of polymer solar cells (PSCs), the manufacture of high-performance large area PSC modules is becoming a critical issue in commercial applications. However, most of the reported light absorption materials and interfacial materials are quite thickness sensitive, with optimal thicknesses of around 100 and 5 nm, respectively. The thickness need to be precisely controlled, otherwise, a small variation in thickness can often lead to a sharp decrease in device performance, especially for interfacial materials. This increases the difficulty of apply these materials in the production of large area PSCs. To avoid the shortcomings of thickness-sensitive materials and achieve high-performance large area PSC modules, we designed and synthesized a series of high mobility donor materials and cathode interfacial materials. These materials exhibited excellent device performance at their optimal thicknesses and maintained high performance even with large thickness variations, thus providing a solution to the bottleneck problem in manufacturing PSC modules and enhancing the device reproducibility. We also developed a simple and efficient approach for achieving a large area cathode interlayer with controlled film composition, uniformity, and thickness at the nanometer-scale using an electrostatic layer-by-layer self-assembly (eLbL) process. The eLbL films exhibited excellent cathode modification ability and can be integrated into the current large area device processing techniques. Thus, our approaches from both material design to device engineering provide new solutions for preparing high-performance large area PSC modules.

Energy levels modulation of small molecule acceptors for polymer solar cells

Improvement of photovoltaic properties of benzo[1,2-b:4,5-b′]difuran-conjugated polymer by side-chain modification

Compared with the quick development of polymer solar cells, achieving high-efficiency small-molecule solar cells (SMSCs) remains highly challenging, as they are limited by the lack of matched materials and morphology control to a great extent. Herein, two small molecules, BSFTR and Y6, which possess broad as well as matched absorption and energy levels, are applied in SMSCs. Morphology optimization with sequential solvent vapor and thermal annealing makes their blend films show proper crystallinity, balanced and high mobilities, and favorable phase separation, which is conducive for exciton dissociation, charge transport, and extraction. These contribute to a remarkable power conversion efficiency up to 13.69% with an open-circuit voltage of 0.85 V, a high short-circuit current of 23.16 mA cm-2 and a fill factor of 69.66%, which is the highest value among binary SMSCs ever reported. This result indicates that a combination of materials with matched photoelectric properties and subtle morphology control is the inevitable route to high-performance SMSCs.

Solar cells based on the photovoltaic effect are an effective method to convert solar energy into electricity. It has become attractive to find solar cell technologies which exhibit lower manufacturing costs by utilizing inexpensive and abundant materials. Some additional advantages conveyed by organic solar cells are that they are lightweight and flexible and allow for scalable material production and cost effective roll-to-roll coating and printing techniques. Efficiency of >10% was disclosed in small area solar cells with various device architectures, which indicated the rapid progress over the last several years and the great potential of organic solar cells as an alternative source of energy. In order for organic solar cells to fully mature from research and development into cost effective products, solar cell technology at a small size needs to be realized at a large scale. And for this, it is highly important to develop new conjugated polymers and understand the fundamental working mechanism of the materials. In the presentation, we developed new conjugated polymers for large-area solar cell technologies and studied the effects of conjugated polymers on solution processing and photovoltaic performance in large area organic solar cells.

This paper presents an intensive review covering all the versatile applications of graphene and its derivatives in solar photovoltaic technology. To understand the internal working mechanism for the attainment of highly efficient graphene-based solar cells, graphene’s parameters of control, namely its number of layers and doping concentration are thoroughly discussed. The popular graphene synthesis techniques are studied. A detailed review of various possible applications of utilizing graphene’s attractive properties in solar cell technology is conducted. This paper clearly mentions its applications as an efficient transparent conducting electrode, photoactive layer and Schottky junction formation. The paper also covers advancements in the 10 different types of solar cell technologies caused by the incorporation of graphene and its derivatives in solar cell architecture. Graphene-based solar cells are observed to outperform those solar cells with the same configuration but lacking the presence of graphene in them. Various roles that graphene efficiently performs in the individual type of solar cell technology are also explored. Moreover, bi-layer (and sometimes, tri-layer) graphene is shown to have the potential to fairly uplift the solar cell performance appreciably as well as impart maximum stability to solar cells as compared to multi-layered graphene. The current challenges concerning graphene-based solar cells along with the various strategies adopted to resolve the issues are also mentioned. Hence, graphene and its derivatives are demonstrated to provide a viable path towards light-weight, flexible, cost-friendly, eco-friendly, stable and highly efficient solar cell technology.

Introduction. The use of renewable energy sources (RES) on open pit rock dumps has the potential to become an important solution for ensuring sustainable development and reducing the negative impact on the environment within mining regions. Methods. Solar and wind energy are among the main RES that can be applied to open pit rock dumps. Solar energy. Open dumps can be an excellent location for solar panels. They can use open space to collect solar energy and generate electricity. With the development of solar cell and solar panel technologies, it becomes possible to increase the efficiency of generating electricity from solar energy sources, making this alternative more and more attractive. Wind energy. Landfills can be an ideal place to install wind energy installations, which will allow wind energy to be used to generate electricity. Wind energy installations should be effectively placed on the top of the dumps. Our Institute is considering the possibility of installing wind energy installations with a vertical axis of rotation, which work efficiently at low wind speeds and produce electricity already at a wind speed of 3-5 m/s. Also, similar wind energy installations are more ecological, they do not create a noise load and are easier to maintain. The results. The use of renewable energy sources on open rock dumps has a number of promising aspects: Energy efficiency is the main advantage of using RES. Excavation rock dumps often have significant dimensions and a high concentration of natural resources. The use of renewable energy sources such as solar and wind energy can provide constant and stable energy capacity for certain processes in mining enterprises. Environmental efficiency. Traditional sources of energy, such as coal or gas, cause significant emissions of pollutants. The use of RES will help to reduce the impact on the environment significantly and to improve the ecological situation in the areas of mining regions. Economic benefits. The use of RES can help reduce the costs of enterprises on traditional energy sources, thereby ensuring economic sustainability. Innovation and development. The introduction of RES can stimulate innovation and the development of new technologies, which ensures the creation of new jobs and supports the economy of the region. Conclusions. The implementation of RES on open rock dumps may require large investments, technical equipment and research. However, this is a profitable solution for providing additional sources of energy, balancing the environmental impact of mining regions, and in the long run, economic benefits. All this will lead to sustainable development of mining regions.