Organic Polymer Solar Cells Research Articles

Fluorinated Benzothiadiazole-Based Polymers for Organic Solar Cells: Progress and Prospects

Fluorinated Benzothiadiazole-Based Polymers for Organic Solar Cells: Progress and Prospects

The Effect of Ethanol Treatment of PEDOT:PSS Hole Transport Layer on the Performance of P3HT: PCBM-Based Solar Cells

The Poly (3,4-ethylenedioxythiophene):poly (styrene sulfonate) (PEDOT:PSS) hole transport layer was treated with ethanol to optimize the performance of poly(3-hexylthiophene) (P3HT): [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) based organic polymer solar cells. Washing out of the insulating PSS from the PEDOT:PSS film by ethanol promoted the formation of a conducting PEDOT chain network so that both the conductivity of PEDOT:PSS film and the properties of P3HT: PCBM-based solar cells were improved significantly.

Isomerization Engineering of Solid Additives Enables Highly Efficient Organic Solar Cells via Manipulating Molecular Stacking and Aggregation of Active Layer.

Morphology control is crucial in achieving high-performance organic solar cells (OSCs) and remains a major challenge in the field of OSC. Solid additive is an effective strategy to fine-tune morphology, however, the mechanism underlying isomeric solid additives on blend morphology and OSC performance is still vague and urgently requires further investigation. Herein, two solid additives based on pyridazine or pyrimidine as core units, M1 and M2, are designed and synthesized to explore working mechanism of the isomeric solid additives in OSCs. The smaller steric hindrance and larger dipole moment facilitate better π-π stacking and aggregation in M1-based active layer. The M1-treated all-small-molecule OSCs (ASM OSCs) obtain an impressive efficiency of 17.57%, ranking among the highest values for binary ASM OSCs, with 16.70% for M2-treated counterparts. Moreover, it is imperative to investigate whether the isomerization engineering of solid additives works in state-of-the-art polymer OSCs. M1-treated D18-Cl:PM6:L8-BO-based devices achieve an exceptional efficiency of 19.70% (certified as 19.34%), among the highest values for OSCs. The work provides deep insights into the design of solid additives and clarifies the potential working mechanism for optimizing the morphology and device performance through isomerization engineering of solid additives.

Synthesis, Characterization and Photovoltaic Properties of Polyplatinaynes with Side Chain Functionalization by Different Electron-Accepting Group

Four new solution-processable platinum-containing polyynes functionalized with triphenylamine backbone and different acceptor fragment in the side chain were synthesized and characterized by spectroscopic, thermal and optical methods. The main- and side-chains show different absorption features in the solar spectrum, resulting in broad absorption coverage of the whole visible region. By changing the acceptor group in the side chain, the photophysical properties including energy levels, absorption wavelength and bandgap of the polymers were finely tuned. As the strength of electron acceptor is increased, the power conversion efficiency (PCE) of organic polymer solar cells fabricated with these polymers as electron donor and (6,6)-phenyl-C61-butyric acid methyl ester (PCBM) as electron acceptor was increased. PCE of 1.35% can be obtained from solar cell based on the polyplatinayne with the dicyanovinyl side group under illumination of an AM 1.5 solar cell simulator in a 1:4 (polymer:PCBM) blend ratio.Graphical

Direct C–H arylation vs Stille polymerization: Rational design, synthesis, and systematic examinations of π-conjugated polymers for organic solar cells

Direct C–H arylation (DA) polymerization, often known as DArP, is an emerging protocol to the synthesis of π-functional polymers that has garnered a lot of attention due to its virtues of requiring a minimum number of synthetic steps and producing a simpler byproduct. However, the regioselectivity of the C–H bonds is significantly less effective in the DArP-derived polymers, which is one of the reasons why only a small number of these polymers exhibit photovoltaic characteristics that are equal to counterparts generated via Stille coupling. In this work, a low-defect π-polymer PBDTF-TPD (DA) is facilely obtained via DArP between 4,8-bis(5-(2-ethylhexyl)-4-fluorothiophen-2-yl)benzo[1,2-b:4,5-b']-dithiophene (BDTF) and thieno [3,4-c]pyrrole-4,6-dione (TPD) that possesses regioselective π-C−H bonds toward arylation. As a result, DArP-derived PBDTF-TPD (DA) and Stille-derived PBDTF-TPD (St) share the similar opto-electrochemical properties, photovoltaic performance, and morphology, indicating that DArP polymerization leads to defined structures with minimal branching defects. Specifically, this study demonstrates that the (PCE = 8.91%) of a rationally designed monomer for DArP using an ideal approach is equivalent to that of the Stille-derived analogue PBDTF-TPD (St, PCE = 9.57%).

Orientation Control of Semiconducting Polymers in Organic Solar Cells

Orientation Control of Semiconducting Polymers in Organic Solar Cells

Organic Optoelectronic Materials: A Rising Star of Bioimaging and Phototherapy.

Recently, many organic optoelectronic materials (OOMs), especially those used in organic light-emitting diodes (OLEDs), organic solar cells (OSCs), and organic field-effect transistors (OFETs), are explored for biomedical applications including imaging and photoexcited therapies. In this review,recently developed OOMs for fluorescence imaging, photoacoustic imaging, photothermal therapy, and photodynamic therapy, are summarized. Relationships between their molecular structures, nanoaggregation structures, photophysical mechanisms, and properties for various biomedical applications are discussed. Mainly four kinds of OOMs are covered: thermally activated delayed fluorescence materials in OLEDs, conjugated small molecules and polymers in OSCs, and charge-transfer complexes in OFETs. Based on the OOMs unique optical properties, including excitation light wavelength and exciton dynamics, they are respectively exploited for suitable biomedical applications. This review is intended to serve as a bridge between researchers in the area of organic optoelectronic devices and those in the area of biomedical applications. Moreover, it provides guidance for selecting or modifying OOMs for high-performance biomedical uses. Current challenges and future perspectives of OOMs are also discussed with the hope of inspiring further development of OOMs for efficient biomedical applications.

Search of electron-rich and electron-deficient building blocks through data mining and library generation for the designing of polymers for organic solar cells

Typical designing of the organic molecules for numerous chemical, biochemical, and electrochemical applications requires extensive human workforce, conceptual intuition, far-reaching academic literature survey, and laborious experimentation. Recently, data-driven approaches, peculiarly machine learning (ML) analysis, have emerged as an alternative methodology to these traditional designing methods. These ML approaches provide robust and quicker way to address the serious restrictions of unavailability of work space, painstaking experimentation, and reduction in the number of experimental trials. In present study, two reference compounds, 5,6-difluoro-2-methylbenzo [d] thiazole and benzo [1,2-b: 3,4-b': 6,5-b''] trithiophene were selected as standard reference compounds. The ChemSpace database was mined for screening the potential effective building blocks and the new libraries of the organic molecules (having high similarity correlation with the reference compounds) were generated for designing the organic solar cell (OSC) devices. The ML analysis was also performed to predict the reorganization energy. The newly designed molecules were further evaluated with respect to their synthetic viability and electronic distribution characteristics to computationally excess the applicability of these novel organic molecules for the OSCs devices. The work presented in this study provides an alternative methodology for the selection of novel organic molecules for developing high-performance OSCs devices.

A Polymer Acceptor with Grafted Small Molecule Acceptor Unit for Efficient All Polymer Organic Solar Cells.

A polymer acceptor, named PX-1, is designed and synthesized using a polymerization strategy with grafted small molecule acceptors. This design approach allows for the freedom of end groups while maintaining efficient terminal packing, enhancing π-π interactions, and facilitating charge transport. All-polymer organic solar cells based on PM6: PX-1 demonstrate a promising efficiency of 13.55%. The result presents an alternative pathway for the design of high-efficiency polymer acceptors through the careful regulation of small molecule acceptor monomers and linker units.

Enhanced efficiency of flexible organic polymer solar cells by incorporation of titanium dioxide nanoparticles

Solar power has quickly become one of the most effective forms of renewable energy today as it provides a clean solution to the growing demand for energy. Most solar panels in the market are rigid as they are made up of metals; therefore, organic polymers provide a flexible alternative. Nanotechnology provides the synthesis of nanoparticles by simple approaches suitable for applications in various fields. Nanoparticles of titanium dioxide (TiO2) were synthesized and characterized in this paper (NPs), which were further incorporated in the construction of a novel, organic polymer solar panel (OPSC) that is flexible and portable; it is made from thylakoid (chloroplast) extract of chard (B. vulgaris subsp. cicla) combined with polystyrene polymer matrix. Insertion of TiO2 NPs in the OPSC improved the current generation compared to the reference devices (OPSC) without TiO2 NPs. Therefore possible uses for the constructed solar panel were suggested. The prepared films were tested for the current generation. Under illumination, the solar panels generated a current of −140 µAp, and −213 µAp without and within TiO2 NPs, respectively. This study opens windows for manufacturing flexible, efficient, and stable organic polymer solar panels.

Virtual screening of efficient building blocks and designing of new polymers for organic solar cells

Designing effective materials for organic solar cells (OSCs) is a challenging and time-consuming process. To achieve high performance OSCs, efficient designing/screening of materials is essential. In recent years, machine learning (ML) has captured the attention of the scientific community working on OSCs. In present study, efficiency of building blocks is predicted by using different ML models. Machine learning analysis is performed for predicting power conversion efficiency (PCE) as a dependent variable and molecular descriptors as independent factors. Moreover, similarity analysis (Tanimoto similarity) is used to screen structures based on the similarity between structures present in the databases and reference (given) structures. RDkit is used to calculate Tanimoto index and compare the fingerprints of molecules present within the database with fingerprint of reference/query structure. The monomer of three famous polymer donors PM6, PBT7-Th and PDPP3T are used as reference molecules for similarity analysis. The best buildings blocks are selected based on the results obtained from similarity analysis. The high efficiency screened building units are connected to design new polymers. PCE values of newly designed monomers are predicted using already trained machine learning models. This proposed framework can screen and design effective polymers for OSCs and predict their PCE without any experimentation in minimum time with marginal computational cost.

Combining ZnO and Organosilica Nanodots as a Thick Cathode Interlayer for Highly Efficient and Stable Inverted Polymer Solar Cells

Low-work-function metal oxides as cathode interlayers are widely used in polymer organic solar cells (PSCs), but the surface defect and intrinsic photocatalysis issues severely affect the high efficiency, thickness insensitivity, and stability of PSCs. In this work, we used organosilica nanodots (OSiNDs) to modify ZnO as cathode interlayers via the self-assembly method. The ZnO/OSiNDs bilayer can acquire a suitable work function and a high conductivity of 5.87 × 10–4 S m–1. Through systematic studies, there is stable surface coordination interaction of Zn–N bonding between ZnO and OSiNDs. In i-PSCs, using D18:Y6 as the active layer, the ZnO/OSiNDs-based device achieves the best PCE of 17.87%. More importantly, due to the high conductivity, the PCE for the device based on a 68 nm thick ZnO/OSiNDs interlayer is still high up to 16.53%, while the PCE for the device based on a 66 nm thick ZnO interlayer is only 13.18%. For photostability, the PCE of the device based on the ZnO/OSiNDs interlayer maintains 95% of its original value after continuous AM 1.5G illumination (contains UV light) at 100 mW/cm2 for 600 min, while that of the ZnO-based device only maintains 72% of the original value. This work suggests that ZnO/OSiNDs can be utilized as a cathode interlayer to fabricate highly efficient and stable PSC over a wide range of thicknesses.

Enhancing the Photovoltaic Properties via Incorporation of Selenophene Units in Organic Chromophores with A2-π2-A1-π1-A2 Configuration: A DFT-Based Exploration

Currently, polymer organic solar cells (POSCs) are widely utilized due to their significant application, such as low-cost power conversion efficiencies (PCEs). Therefore, we designed a series of photovoltaic materials (D1, D2, D3, D5 and D7) by the incorporation of selenophene units (n = 1-7) as π1-spacers by considering the importance of POSCs. Density functional theory (DFT) calculations were accomplished at MPW1PW91/6-311G (d, p) functional to explore the impact of additional selenophene units on the photovoltaic behavior of the above-mentioned compounds. A comparative analysis was conducted for designed compounds and reference compounds (D1). Reduction in energy gaps (∆E = 2.399 - 2.064 eV) with broader absorption wavelength (λmax = 655.480 - 728.376 nm) in chloroform along with larger charge transference rate was studied with the addition of selenophene units as compared to D1. A significantly higher exciton dissociation rate was studied as lower values of binding energy (Eb = 0.508 - 0.362 eV) were noted in derivatives than in the reference (Eb = 0.526 eV). Moreover, transition density matrix (TDM) and density of state (DOS) data also supported the efficient charge transition origination from HOMOs to LUMOs. Open circuit voltage (Voc) was also calculated for all the aforesaid compounds to check the efficiency, and significant results were seen (1.633-1.549 V). All the analyses supported our compounds as efficient POSCs materials with significant efficacy. These compounds might encourage the experimental researchers to synthesize them due to proficient photovoltaic materials.

Ultrafast Electron Transfer Dynamics of Organic Polymer Nanoparticles with Graphene Oxide.

We prepared organic polymer poly-3-hexylthiophene (p3ht) nanoparticles (NPs) and graphene oxide (GO)/reduced graphene oxide (RGO) composites p3ht NPs-GO/RGO by using the reprecipitation method. We demonstrated that GO/RGO could improve the ordering and planarity of p3ht chains as well as the formation of p3ht NPs, and confirmed the effects of GO/RGO on the fluorescence and carrier transport dynamics of p3ht NPs by using femtosecond fluorescence upconversion and transient absorption (TA) techniques. Ultrafast electron transfer (∼1 ps) between GO/RGO and p3ht NPs quenched the fluorescence of p3ht NPs, indicating excellent properties of p3ht NPs-GO/RGO as the charge transfer complexes. Efficient electron transfer may promote the applications of p3ht NPs-GO/RGO composites in organic polymer solar cells and photocatalysis. Moreover, RGO had stronger interfacial interactions and more matched conduction band energy levels with p3ht NPs than GO did, which implied that p3ht NPs-RGO might have greater application values than p3ht NPs-GO.

Benzo[1,2‐b:4,5‐b′]Difuran‐Based Polymer for Organic Solar Cells with 17.5% Efficiency via Halogenation‐Mediated Aggregation Control

AbstractThe realization of high‐efficiency organic solar cells (OSCs) from renewable sources will bring a real green energy technology. Benzo[1,2‐b:4,5‐b′]difuran (BDF) is such a building block for photovoltaic polymers as it can be built from furfural, which is available from trees and vegetables. However, the device performance of BDF‐based polymers is limited by aggregation properties and unfavorable active layer morphology. Herein, two new BDF‐based wide bandgap‐conjugated polymers, PFCT‐2F and PFCT‐2Cl, are developed by copolymerizing the fluorinated or chlorinated BDF units with the 3‐cyanothiophene unit for use as electron donors in OSCs. Benefitting from the more rotatable nature of the side‐chain thiophene rings on the BDF unit, PFCT‐2Cl exhibits more adjustable aggregation, higher π–π stacking ordering, and appropriate miscibility with the electron acceptor. As a result, a high power conversion efficiency (PCE) of 17.2% is offered by PFCT‐2Cl, which is nearly two times higher than that of PFCT‐2F (8.9%). A more remarkable PCE up to 17.5% is further achieved by PFCT‐2Cl in a ternary OSC, which is the new efficiency record for BDF‐based polymers. This success proves the critical role of aggregation control in BDF‐based polymers and the bright future for constructing high‐performance OSCs from bio‐renewable sources.

BDT-based donor polymer for organic solar cells to achieve high efficiency over 15% for ternary organic solar cells

BDT-based donor polymer for organic solar cells to achieve high efficiency over 15% for ternary organic solar cells

A study of the use of carbonyl and ester groups in regulating the optical and electrical characteristics of wide bandgap polymers for organic solar cells

The use of the carbonyl group is proposed in the design of wide bandgap polymers due to its stronger electron withdrawing ability compared with the ester group that can achieve a higher VOC.

Nonlinear Analysis of Organic Polymer Solar Cells Using Differential Quadrature Technique with Distinct and Unique Shape Function

Nonlinear Analysis of Organic Polymer Solar Cells Using Differential Quadrature Technique with Distinct and Unique Shape Function

Study on Optical Efficiency of Organic Photovoltaic Devices with Multi-Tip Metal Nanostructures

As a new generation of photovoltaic devices, organic polymer solar cell (Organic Solar Cell, OSC) have attracted wide attention of researchers in recent years because of their unique advantages such as simple process, low energy consumption, low cost and large area preparation. However, the development of OSC has encountered bottlenecks: the low carrier mobility of photovoltaic materials forces the thickness of the active layer of OSC to be reduced as much as possible to meet the requirements of effective collection of photogenerated carriers, while the thinner absorption layer will lead to serious optical absorption loss and device performance degradation. Therefore, how to enhance the optical absorptivity of OSC on the premise of effective carrier collection has become a research hot-spot. Based on this characteristic, with the help of finite element method, the structure model of OSC with multi-tip metal nanoparticles is established, and the effects of metal nanospheres and star particles on OSC light absorption factors are studied systematically. Firstly, the effects of introducing metal nanoparticles into different functional layers of OSC (active layer and buffer layer) are compared and analyzed to determine the introduction location of metal nanoparticles in OSC. Secondly, the localized resonance enhancement rules of spherical and cubic metal nanoparticles in the functional layer are discussed. Combined with the theoretical model, the optimal design method of metal nanoparticles structure parameters (size and period) is established. The results show that the absorption enhancement of metal nanoparticles in the active layer of OSC is higher than that in the buffer layer. On the one hand, it can stimulate more electron hole pair separation, improve the separation rate of electron hole pair, on the other hand, it can also make the separated electron hole to obtain more energy, recombination becomes relatively difficult, and the arrival rate of the battery electrode is improved.

An Anthradithiophene Donor Polymer for Organic Solar Cells with a Good Balance between Efficiency and Synthetic Accessibility

Over the past few years, the organic photovoltaics technology (OPV) has reached remarkable power conversion efficiencies (PCEs), mostly thanks to the advent of nonfullerene acceptors as well as to a high level of materials engineering. Yet, the complex materials syntheses behind these results ultimately limit technological readiness. The quest for scalable organic compounds offering high PCE and reasonably low synthetic complexity is a must to close the gap between laboratory R&D and commercial products. The synthesis and full characterization of a new conjugated polymer called PATTD is reported herein, based on a novel anthradithiophene as an electron‐rich building block coupled with a commercially available dithienylbenzodithiophenedione as an electron‐withdrawing comonomer. Its photovoltaic properties are studied in blends with IT‐4F and IDIC as acceptors. PATTD:IT‐4F‐based photovoltaic devices exhibit a PCE approaching 10% and over 2300 h shelf‐life stability. The PATTD scalability factor (SF), together with the PATTD‐based photovoltaic performances, lead to a PCE/SF value equal to 0.297, placing such devices into the innermost circle of OPV materials, achieving one of the best compromises between efficiency and synthetic complexity and at the same time offering promising industrial perspectives.