Facile Strategy for Reducing Cell-to-Module Efficiency Gap in Organic Solar Cells by Controlling the Preaggregation of Photoactive Solutions.

Organic solar cells (OSCs) have recently achieved efficiencies of >20% in single-junction unit cells owing to rapid advancements in materials and device technologies. Large-area OSCs face several challenges that adversely affect their efficiency compared to small unit cells. These challenges include increased resistance loads derived from their larger dimensions, as well as limitations related to morphology, miscibility, and crystallinity.

A 3-Fluoropyridine Manipulating the Aggregation and Fibril Network of Donor Polymers for Eco-Friendly Solution-Processed Versatile Organic Solar Cells.

The development of eco-friendly solvent-processed organic solar cells (OSCs) suitable for industrial-scale production should be now considered the imperative research. Herein, asymmetric 3-fluoropyridine (FPy) unit is used to control the aggregation and fibril network of polymer blends. Notably, terpolymer PM6(FPy = 0.

Bihalogenated Thiophene-Based Terpolymers for High-Performance Semitransparent Organic Solar Cells Processed by an Eco-Friendly Solvent and Layer-by-Layer Deposition.

The development of photoactive materials simultaneously satisfying high performance, low cost, and eco-friendly processability remains challenging in organic solar cells (OSCs). Herein, a synergistic strategy is proposed to design three terpolymers (PM7(ClCl = 0.2), PM7(ClBr = 0.

Tailoring Microstructure and Morphology via Sequential Fluorination to Enhance the Photovoltaic Performance of Low-Cost Polymer Donors for Organic Solar Cells.

For utilizing organic solar cells (OSCs) for commercial applications, reducing the overall cost of the photo absorbent materials is also very crucial. Herein, such a challenge is addressed by synergistically controlling the amount of fluorine (F)-substituents (n = 2, 4) on a low-cost wide-bandgap molecular design involving alternate fluorinated-thienyl benzodithiophene donor and 2,5-difluoro benzene (2FBn) or 2,3,5,6 tetrafluorobenzene (4FBn) to form two new polymer donors PBDT-2FBn and PBDT-4FBn, respectively. As expected, sequential fluorination causes a lowering of the frontier energy levels and planarization of polymer backbone via F···S and C-H···F noncovalent molecular locks, which results in more pronounced molecular packing and enhanced crystallinity from PBDT-2FBn to PBDT-4FBn.

Water-Repellent Perovskites Induced by a Blend of Organic Halide Salts for Efficient and Stable Solar Cells.

Despite tremendous progress in the power conversion efficiency (PCE) of perovskite solar cells (PeSCs), the long-term stability issue remains a significant challenge for commercialization. In this study, by blending organic halide salts, phenylethylammonium halide (PEAX, X = I, Br), with CHNHPbI (MAPbI), we achieved remarkable enhancements in the water-repellency of perovskite films and long-term stability of PeSCs, together with enhanced PCE. The hydrophobic aromatic PEA group in PEAX protects the perovskite film from destruction by water.

Printable and Semitransparent Nonfullerene Organic Solar Modules over 30 cm Introducing an Energy-Level Controllable Hole Transport Layer.

For the commercialization of organic solar cells (OSCs), the fabrication of large-area modules a solution process is important. The fabrication of OSCs a solution process using a nonfullerene acceptor (NFA)-based photoactive layer is limited by the energetic mismatch and carrier recombination, reducing built-in potential and effective carriers. Herein, for the fabrication of high-performance NFA-based large-area OSCs and modules a solution process, hybrid hole transport layers (h-HTLs) incorporating WO and MoO are developed.

Understanding the Critical Role of Sequential Fluorination of Phenylene Units on the Properties of Dicarboxylate Bithiophene-Based Wide-Bandgap Polymer Donors for Non-Fullerene Organic Solar Cells.

Design and development of wide bandgap (WBG) polymer donors with low-lying highest occupied molecular orbitals (HOMOs) are increasingly gaining attention in non-fullerene organic photovoltaics since such donors can synergistically enhance power conversion efficiency (PCE) by simultaneously minimizing photon energy loss (E ) and enhancing the spectral response. In this contribution, three new WBG polymer donors, P1, P2, and P3, are prepared by adding phenylene cores with a different number of fluorine (F) substituents (n = 0, 2, and 4, respectively) to dicarboxylate bithiophene-based acceptor units. As predicted, fluorination effectively aides in the lowering of HOMO energy levels, tailoring of the coplanarity and molecular ordering in the polymers.

High-Performance Nonfullerene Organic Photovoltaics Applicable for Both Outdoor and Indoor Environments through Directional Photon Energy Transfer.

With the advent of the smart factory and the Internet of Things (IoT) sensors, organic photovoltaics (OPVs) gained attention because of their ability to provide indoor power generation as an off-grid power supply. To satisfy these applications, OPVs must be capable of power generation in both outdoor and indoor at the same time for developing environmentally independent devices. For high performances in indoor irradiation, a strategy that maximizes photon utilization is essential.

Design Principles and Synergistic Effects of Chlorination on a Conjugated Backbone for Efficient Organic Photovoltaics: A Critical Review.

The pursuit of low-cost, flexible, and lightweight renewable power resources has led to outstanding advancements in organic solar cells (OSCs). Among the successful design principles developed for synthesizing efficient conjugated electron donor (ED) or acceptor (EA) units for OSCs, chlorination has recently emerged as a reliable approach, despite being neglected over the years. In fact, several recent studies have indicated that chlorination is more potent for large-scale production than the highly studied fluorination in several aspects, such as easy and low-cost synthesis of materials, lowering energy levels, easy tuning of molecular orientation, and morphology, thus realizing impressive power conversion efficiencies in OSCs up to 17%.

Enhanced chemical and physical properties of PEDOT doped with anionic polyelectrolytes prepared from acrylic derivatives and application to nanogenerators.

Acrylic monomers, 4-hydroxybutyl acrylate (HBA) and 2-carboxyethyl acrylate (CEA), were each co-polymerized with styrene sulfonate in 10 mol% ratio to synthesize two types of anionic polyelectrolytes, P(SS--HBA) and P(SS--CEA), respectively. Through oxidative polymerization, two types of PEDOT composites (PEDOT:P(SS--HBA) and PEDOT:P(SS--CEA)) were synthesized, to which the anionic templates were applied as dopants. The composites were similar to PEDOT:PSS; however, crosslinking occurred with an increase in annealing temperature after film casting, which increased the electrical conductivity and hydrophobicity.

13.9%-Efficiency and Eco-Friendly Nonfullerene Polymer Solar Cells Obtained by Balancing Molecular Weight and Solubility in Chlorinated Thiophene-Based Polymer Backbones.

To industrialize nonfullerene polymer solar cells (NFPSCs), the molecular design of the donor polymers must feature low-cost materials and a high overall yield. Two chlorinated thiophene-based polymers, P(F-Cl) and P(Cl-Cl), are synthesized by introducing halogen effects like fluorine (F) and chlorine (Cl) to the previously reported P(Cl), which exhibits low complexity. However, the molecular weights of these polymers are insufficient owing to their low solubility, which in turn is caused by introducing rigid halogen atoms during the polymerization.

Drastic Changes in Properties of Donor-Acceptor Polymers Induced by Asymmetric Structural Isomers for Application to Polymer Solar Cells.

Appropriate design of donor-acceptor (D-A) conjugated polymers is important for enhancing their physical, optical, and electrochemical properties. The rapid development of D-A conjugated polymers based on fullerene and nonfullerene derivatives in the past decade has led to an improvement in the performance of polymer solar cells (PSCs). In this study, we designed and synthesized two donor polymers based on the DTffBT acceptor unit, with matching optical absorption range and energy levels with fullerene (PCBM) and nonfullerene acceptors (ITIC and IDIC), by introducing asymmetric structural isomers of donor units.

A 3-Fluoro-4-hexylthiophene-Based Wide Bandgap Donor Polymer for 10.9% Efficiency Eco-Friendly Nonfullerene Organic Solar Cells.

Nonfullerene organic solar cells (NFOSCs) are attracting increasing academic and industrial interest due to their potential uses for flexible and lightweight products using low-cost roll-to-roll technology. In this work, two wide bandgap (WBG) polymers, namely P(fTh-BDT)-C6 and P(fTh-2DBDT)-C6, are designed and synthesized using benzodithiophene (BDT) derivatives. Good oxidation stability and high solubility are achieved by simultaneously introducing fluorine and alkyl chains to a single thiophene (Th) unit.

Effect on Electrode Work Function by Changing Molecular Geometry of Conjugated Polymer Electrolytes and Application for Hole-Transporting Layer of Organic Optoelectronic Devices.

In this study, we synthesized three conjugated polymer electrolytes (CPEs) with different conjugation lengths to control their dipole moments by varying spacers. P-type CPEs (PFT-D, PFtT-D, and PFbT-D) were generated by the facile oxidation of n-type CPEs (PFT, PFtT, and PFbT) and introduced as the hole-transporting layers (HTLs) of organic solar cells (OSCs) and polymer light-emitting diodes (PLEDs). To identify the effect on electrode work function tunability by changing the molecular conformation and arrangement, we simulated density functional theory calculations of these molecules and performed ultraviolet photoelectron spectroscopy analysis for films of indium tin oxide/CPEs.

Enhanced Photovoltaic Properties of Bulk Heterojunction Organic Photovoltaic Devices by an Addition of a Low Band Gap Conjugated Polymer.

In this study, we fabricated organic photovoltaics (OPVs) by introducing the polymer additive HTh6BT into the photoactive layer of a poly(3-hexylthiophene):phenyl-C-butyric acid methyl ester (P3HT:PCBM) system. The HTh6BT had a relatively low band gap energy of 1.65 eV and a molecular and crystalline structure similar to that of P3HT.

A Simple Approach to Fabricate an Efficient Inverted Polymer Solar Cell with a Novel Small Molecular Electrolyte as the Cathode Buffer Layer.

A novel small-molecule electrolyte, 1,1'-bis(4-hydroxypropyl)-[4,4'-bipyridine]-1,1'-diium bromide (V-OH), containing a mixture of PTB7:PCBM has been designed and synthesized as a cathode buffer layer for inverted polymer solar cells (iPSCs). The molecular structure of this new compound comprises a viologen skeleton with hydroxyl group terminals. While the viologen unit is responsible for generating a favorable interface dipole, the two terminal hydroxyl groups of V-OH may generate a synergy effect in the magnitude of the interface dipole.

Improvement in Half-Life of Organic Solar Cells by Using a Blended Hole Extraction Layer Consisting of PEDOT:PSS and Conjugated Polymer Electrolyte.

In this study, we fabricated conventional structured organic solar cells (OSCs) by introducing a hole extraction layer (HEL) that consisted of poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) and conjugated polymer electrolyte (CPE) poly[9,9-bis(4'-sulfonatobutyl)fluorene-alt-thiophene] (PFT-D). PFT-D has a -SO functional group that acts as a conjugate base against the -SOH of PSS. In addition, the molecular dipole of PFT-D can screen the Coulombic attraction between PEDOT chains and PSS chains.

Rapid double-dye-layer coating for dye-sensitized solar cells using a new method.

Intensive research with the specific aim of developing inexpensive renewable energy sources is currently being undertaken. In dye-sensitized solar cell (DSSC) production, the most time-consuming process is coating the dye on working electrodes: absorption of ruthenium-based dyes [e.g.

Synthesis and characterization of a fluorene-quinoxaline copolymer for light-emitting applications.

A conjugated copolymer based on 9,9-dioctyl-fluorene and 2,3-bis(4-(hexyloxy)phenyl) quinoxaline has been synthesized by the palladium-catalyzed Suzuki coupling reaction. The synthesized polymer was soluble in common organic solvents such as chloroform, THF, and toluene and had good film properties. The polymer was analyzed by 1H-NMR spectroscopy, UV-vis spectroscopy, GPC, TGA, DSC, and cyclic voltammetry.