Search Results (271)

Additive engineering has become a critical strategy for optimizing the morphology and performance of bulk heterojunction (BHJ) organic solar cells (OSCs), while volatile solid additives have been widely employed to control nanoscale phase separation during film formation. Concerns regarding reproducibility, residual solvent effects, and long-term stability have stimulated increasing interest in non-volatile solid additives. In recent years, solid additive engineering has emerged as a promising approach for modulating molecular packing, regulating phase separation, enhancing charge transport, and improving device stability. However, a systematic analysis of its material design principles and performance impact remains limited. This review summarizes recent progress in solid additive engineering for OSCs, categorizing reported additives into non-volatile, volatile and nanomaterials. The effects of these additives on key photovoltaic parameters, including open-circuit voltage (Voc), short-circuit current density (Jsc), fill factor (FF), and power conversion efficiency (PCE), are comparatively analyzed based on the reported data. Particular emphasis is placed on morphology and structural performance relationships and stability enhancement mechanisms. Finally, current challenges, including the lack of universal molecular design rules and limited mechanistic understanding of additive host interactions, are discussed, and future research directions are proposed. This review aims to provide a comprehensive perspective on the material-level role of solid additives and to guide the rational design of next-generation high-performance and stable organic solar cells. Full article

In bulk heterojunction (BHJ) organic solar cells (OSCs) employing perylene diimide (PDI)-based non-fullerene acceptors, excessive intermolecular interactions among PDI units lead to severe aggregation and pronounced donor–acceptor phase separation, both of which critically limit device performance. To address these issues, numerous structurally engineered PDI derivatives have been developed. In particular, twisted multi-PDI architectures designed to suppress intermolecular aggregation have shown improved morphological control; however, such twisted structures are often highly amorphous, which reduces electron-transport efficiency and constrains OSC performance. In this work, we introduce a mixed-acceptor strategy combining a twisted PDI dimer (SF-PDI₂) with a planar monomeric PDI (m-PDI) to balance aggregation and morphological uniformity. Ternary blend OSCs consisting of PTB7-Th as the donor and these two PDI acceptors exhibit systematic performance variations depending on their relative ratios. At the optimized composition (SF-PDI₂:m-PDI = 90:10 by weight), the device outperforms single-acceptor systems, which is attributed to controlled aggregation arising from the complementary structural features of the two PDI acceptors. This study demonstrates that combining mixed PDI acceptors with similar molecular moieties enables precise control of aggregation, improving both morphology and photovoltaic performance. Full article

Integrating functional perovskites on an amorphous microchannel plate (MCP) glass faces challenges regarding the lack of ordered nucleation sites and stringent thermal budgets. Herein, we propose a surface energetics-based atomic layer deposition (ALD) strategy to achieve template-assisted oriented BaTiO₃ growth via a (101)-oriented anatase TiO₂ seed layer. Systematic investigation of the TiCl₄/O₃ process reveals a kinetic-to-thermodynamic transition at 300 °C, triggering a singular (101) preferred orientation. Combined DFT calculations and Wulff construction elucidate that this texture evolution is governed by a thermally activated surface energy minimization mechanism, driven by the intrinsic stability of the (101) facet. Crucially, the optimized seed layer acts as a multifunctional template: it not only transforms BaTiO₃ growth from random polycrystalline morphology to a singular (100) orientation with suppressed bulk carbonate impurities but also ensures excellent conformality and uniformity throughout the high aspect ratio microchannels. This study clarifies the thermodynamic mechanism of oriented growth on amorphous substrates, providing a versatile surface engineering pathway for constructing high-performance MCP-based heterojunction devices. Full article

We report a comprehensive spectroscopic, microscopic, and device-level investigation of the ambient-driven degradation of PTQ10:IDIC bulk-heterojunction organic solar cells (BHJ-OSCs), up to 500 h. The power conversion efficiency dropped from 9.51% to 7.69% (≈19% relative loss), primarily due to a decrease in short-circuit current density (J_SC 15.93 to 13.82 mA cm⁻²), while the open-circuit voltage remained largely stable (0.92 to 0.90 V). Atomic force microscopy reveals surface smoothing upon ageing, with the root-mean-square roughness decreasing from 4.29 to 3.45 nm, and the UV–vis absorption spectra show negligible changes, indicating preserved bulk light-harvesting capability. In contrast, X-ray photoelectron spectroscopy indicates pronounced surface compositional evolution, with a decrease in oxygen (5.18 to 3.18%) and a substantial increase in fluorine content (3.23 to 7.23%), consistent with fluorine-rich surface segregation or reorientation. Ultraviolet photoelectron spectroscopy further reveals a 0.48 eV reduction in surface work function, indicative of surface dipole modification and near-surface electronic reorganization. Collectively, these results demonstrate that ambient ageing primarily impacts interfacial chemistry and morphology rather than bulk optoelectronic properties, highlighting interfacial engineering and encapsulation as effective strategies for improving long-term device stability. Full article

Focusing on PM6 as the electron-donating polymer and the non-fullerene acceptors Y12 and PY-IT, this study investigates their chemical, optical, and morphological properties, as well as their compatibility in bulk heterojunction (BHJ) architectures. All materials were characterized in thin-film form using Fourier transform infrared (FTIR), and Raman spectroscopy. Binary blends of PM6:Y12 and PM6:PY-IT, along with the ternary PM6:PY-IT:Y12 system, were dissolved in o-xylene and processed into active layers by blade coating under ambient conditions. Optical properties were analyzed in solution and in thin films, providing insights into light-absorption efficiency and spectral complementarity. Nanoscale morphology and molecular packing were examined using atomic force microscopy (AFM) and grazing-incidence wide-angle X-ray scattering (GIWAXS), revealing correlations between material organization and device performance. The results highlight the importance of optimizing material selection, ink formulation, and film morphology to maximize charge-generation efficiency. Power-conversion efficiencies (PCEs) of 13.95%, 12.04%, and 12.17% were achieved for PM6:Y12, PM6:PY-IT, and PM6:PY-IT:Y12 devices, respectively. The ternary PM6:PY-IT:Y12 system demonstrated performance comparable to PM6:PY-IT, with improved miscibility and nearly aggregate-free morphologies, suggesting potential for further efficiency gains. These findings offer valuable guidance for designing high-performance, sustainable active layers, contributing to the development of next-generation organic photovoltaic technologies. Full article

Zinc(II) bis(8-hydroxyquinolinate) (Zn(HQ)₂) and 1,10-phenanthroline (phen) were combined to fabricate an organic semiconductor in a bulk heterojunction architecture and subsequently embedded in a poly 3,4-ethylene dioxythiophene–polystyrene sulfonate (PEDOT–PSS) matrix. The resulting Zn(HQ)₂-phen/PEDOT–PSS was deposited as a film upon tin-oxide-coated glass and graphite-covered Tetra Pak (TP)-recycled substrates for the manufacture of organic photoconductive devices. The topographical and micromechanical characteristics of the hybrid films were assessed by atomic force microscopy, with an average roughness of 5.6 nm, maximum tensile strength of 7.95 MPa, and Knoop microhardness of 14.7. The fundamental energy gap (E_g) was determined employing the Kubelka–Munk function, with E_g of 3.5–3.8 eV. These results were complemented with a computational DFT molecular orbital analysis of the species involved in the hybrid semiconductor. The devices were electrically characterized under UV irradiation conditions, obtaining the current–voltage and power–voltage relationships. The maximum current in the TP–graphite device is 1.8 × 10⁻² A and 1.1 × 10⁻² A in the device on glass–ITO. Zn(HQ)₂-phen/PEDOT–PSS film presents its own operating regimes relating to a photoconductor or flexible photoresistor. The power in the device on glass–ITO is 120 mW and 113 mW for shortwave and longwave, respectively, and in the device on TP–graphite, it is 198 mW and 139 mW. Full article

The efficiency of organic solar cells is constantly improving thanks to more advanced materials. Electron donor polymers, such as PM6 and its derivatives, as well as non-fullerene acceptors (NFAs) Y6 and ITIC and their derivatives, have become the standard materials for organic solar cell studies. To broaden the absorption range of solar cells, so-called ternary organic solar cells have been developed, which add a third material to the active layer. In this work, two chromophores based on the derivatives of the Janus-dione (s-indacene-1,3,5,7(2H,6H)-tetraone) central acceptor fragment, namely TIIC-1 and TIIC-2, were synthesized. Materials were characterized using theoretical and experimental methods, including UV-Vis absorption measurements, cyclic voltammetry, photoemission yield spectroscopy, and photoconductivity. The materials were incorporated as ternary components in PM6:Y7 bulk heterojunction solar cells. The power conversion efficiency (PCE) of PM6:Y7:TIIC-1 ternary solar cells was improved compared to binary PM6:Y7 reference cells. The PCE increased from 11.9% in binary blends to 12.5% in ternary cells. This increase is attributed to the cascade-like energy level arrangement, which facilitates charge transfer in the photoactive layer. Full article

We report a notable enhancement in the performance of small-molecule-based organic photovoltaics (OPVs) through the use of a ternary blend comprising a small-molecule donor (DTS(FBTTh₂)₂), a polymer donor (PBDTTT-EFT), and a fullerene acceptor (PC₇₁BM). By optimizing the composition of this ternary active layer, we achieved a significant increase in power conversion efficiency from 7.99% to 9.08%. This improvement is attributed to the broader light absorption spectrum and enhanced charge transport pathways provided by the polymeric donor. PBDTTT-EFT optimizes the nanomorphology and ordering of the bulk heterojunction films and forms a cascade energy level that enhances charge carrier mobility. Our results demonstrate that semiconducting polymer donors can effectively control light absorption, charge transport, and exciton dissociation by optimizing morphology and crystallinity. This approach offers new possibilities for advancing the performance of various optoelectronic devices through strategic use of different semiconducting polymer donors. Full article

Novel A-D-A (acceptor–donor–acceptor)-type molecules were synthesized and tested in organic photovoltaics (OPV) devices. For a pristine film of compound 1b with a 2,2′-(naphtho[2,3-b]thiophene-4,9-diylidene)dipropanedinitrile A unit and carbazole-based donor D unit, efficient exciton splitting by intermolecular electron transfer was proved. The observation of the out-of-phase electron spin echo in the pristine 1b film unambiguously testifies to a high yield of charge-transfer state formation. Despite this, the yield of free charge generation in pristine 1b is low due to the fast geminate and non-geminate recombination. This process is detrimental for OPV performance when the compound capable of exciton self-splitting is used as an acceptor component of the bulk heterojunction (BHJ) active layer because of the fast charge recombination within this component. Exciton self-splitting can be of general significance for push–pull OPV acceptors or donors in bulk heterojunctions, although it can be masked by other photophysical processes in the BHJ active layer. This is the reason why molecules with a strong intermolecular charge-transfer band are not suitable components of the active layer of efficient OPV devices. Full article

Thin-film organic solar cells (TFOSCs) are gaining momentum as next-generation photovoltaic technologies due to their lightweight nature, mechanical flexibility, and low cost-effective fabrication. In this pioneering study, we report for the first time the incorporation of cobalt-doped zinc sulfide $(\mathrm{Z}\mathrm{n}\mathrm{S}/\mathrm{C}\mathrm{o})$ nanoparticles (NPs) into a poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) bulk-heterojunction photoactive layer. $\mathrm{Z}\mathrm{n}\mathrm{S}/\mathrm{C}\mathrm{o}$ NPs were successfully synthesized via a wet chemical method and integrated at varying concentrations (1%wt, 3%wt, and 5%wt) to systematically investigate their influence on device performance. The optimal doping concentration of 3%wt yielded a remarkable power conversion efficiency (PCE) of 4.76%, representing a 102% enhancement over the pristine reference device (2.35%) under ambient laboratory conditions. The observed positive trend is attributed to the localized surface plasmon resonance (LSPR) effect and near-field optical enhancement induced by the presence of ZnS/Co NPs in the active layer, thereby increasing light-harvesting capability and exciton dissociation. Comprehensive morphological and optical characterizations using high-resolution scanning electron microscopy (HRSEM), high-resolution transmission electron microscopy (HRTEM), and spectroscopic techniques confirmed uniform nanoparticle dispersion, nanoscale crystallinity, and effective light absorption. These findings highlight the functional role of $\mathrm{Z}\mathrm{n}\mathrm{S}/\mathrm{C}\mathrm{o}$ NPs as dopants in enhancing TFOSC performance, providing valuable insights into optimizing nanoparticle concentration. This work offers a scalable and impactful strategy for advancing high-efficiency, flexible, and wearable organic photovoltaic devices. Full article

Developing efficient photocatalysts is essential for sustainable wastewater treatment and tackling global water pollution. Graphitic carbon nitride (g-C₃N₄) is a promising material because it is active under visible light and chemically stable. However, its practical application is limited by fast recombination of charge carriers and a low surface area. In this study, we report a simple hydrothermal method to synthesize exfoliated porous g-C₃N₄ (E-PGCN) combined with Ti₃C₂ MXene to form a heterojunction composite that addresses these issues. Various characterization techniques (FTIR, XRD, XPS, SEM, BET) confirmed that adding MXene improves light absorption, increases surface area (53.7 m²/g for the composite versus 21.4 m²/g for bulk g-C₃N₄ (BGCN)), and enhances charge separation at the interface. Under UV-visible light irradiation with Rhodamine B (RhB) as the model pollutant, the E-PGCN/Ti₃C₂ MXene composite containing 3 wt% MXene demonstrated an impressive degradation efficiency of 93.2%. This performance is superior to BGCN (66.6%), E-PGCN (82.5%), and E-PGCN/Ti₃C₂ MXene-5 wt% composites (81%). This is due to the excess Mxene which caused agglomeration and reduced activity. Scavenger studies identified electron radicals as the dominant reactive species, with optimal activity at pH ~4.5. This enhanced performance, 1.4 times greater than BGCN and 1.13 times higher than E-PGCN, is ascribed to the synergistic interplay between the excellent electrical conductivity of MXene and the porous structural features of E-PGCN. This work highlights the importance of morphological engineering and heterojunction design for advancing metal-free photocatalysts, offering a scalable strategy for sustainable water purification. Full article

This study presents a computational investigation into the design of triphenylamine-based donor chromophores incorporating 2-(1,1-dicyanomethylene)rhodanine as the acceptor unit. Three molecular architectures (System-1 to System-3) were developed by introducing distinct thiophene-derived $\pi$-bridges to modulate their electronic and optical characteristics for potential application in bulk heterojunction organic solar cells (OSCs). Geometrical optimizations were performed at the B3LYP/6-31+G(d,p) level, while excited-state and absorption properties were evaluated using TD-DFT with the CAM-B3LYP functional. Frontier orbital analysis revealed efficient charge transfer from donor to acceptor moieties, with System-3 showing the narrowest HOMO–LUMO gap (1.96 eV) and the lowest excitation energy (2.968 eV). Charge transport properties, estimated from reorganization energies, indicated that System-2 exhibited the most favorable balance for ambipolar transport, featuring the lowest electron reorganization energy (0.317 eV) and competitive hole mobility. Photovoltaic parameters calculated with PC₆₁BM as acceptor predicted superior $V_{oc}$, $J_{sc}$, and fill factor values for System-2, resulting in the highest theoretical power conversion efficiency (10.95%). These findings suggest that $\pi$-bridge engineering in triphenylamine-based systems can significantly enhance optoelectronic performance, offering promising donor materials for next-generation OSC devices. Full article

This work introduces a general solution for printing wavelength-selective bulk-heterojunction photosensitive organic field effect transistors (PS-OFETs) by addressing electrode thickness variation and the feasibility of color selectivity in detecting incident light. The inkjet-printed silver electrode thickness was varied from 125 to $950 \mathrm{n}\mathrm{m}$ by multilayer printing. PIF, IDFBR, and ITIC-4F were chosen as the active semiconductor materials with complementary optical absorption. Results indicate that PS-OFETs exhibit the best functionality at an electrode thickness of approximately $325 \mathrm{n}\mathrm{m}$ and an active material combination with PIF:IDFBR (1:1). For the $540 \mathrm{n}\mathrm{m}$ wavelength, a responsivity of $55 \mathrm{m}\mathrm{A}{\mathrm{W}}^{-1}$ was obtained. This is four-fold higher than the photoresponse obtained at $700 \mathrm{n}\mathrm{m}$. Full article

With the aim of reducing catalysts’ cost while maintaining high performance in water splitting, ZnO and RuO₂ were combined into composites with ZnO to RuO₂ mass ratios of 1:1, 2:1, and 10:1. The ZnO/RuO₂ composites were prepared by microwave processing of a suspension containing Zn(OH)₂ in situ precipitated onto RuO₂ powder, and subsequently thermally modified at 600 °C to promote heterojunction formation and alter the defect chemistry. Phase composition, crystal structure, morphology, and optical properties were analyzed in detail employing XRD, TEM/HRTEM, HAADF-STEM with EDS, PL and XPS spectroscopy. The photoelectrocatalytic (PEC) activity of the composites toward the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) was evaluated by linear sweep voltammetry in alkaline electrolyte (0.1 M NaOH, pH 13), before and after one hour of electrochemical system illumination. The analysis focused on surface and bulk oxygen vacancies, which may have a crucial impact in PEC activity, by (1) promoting charge separation and increasing the number of active sites thus enhancing PEC activity, or (2) acting as electron–hole traps and recombination centers, reducing the lifetime of photo-induced charge carriers and thus deteriorating PEC activity. The presented results demonstrate that the combination of ZnO with RuO₂ in a specific mass ratio, along with controlled defect structure, offers a worthwhile route for developing bifunctional, noble-metal-reduced catalysts for green hydrogen and oxygen production. Full article

A series of novel discotic liquid crystalline donor–acceptor hybrid heterojunctions were prepared by blending the triphenylene derivative (T5E36) as donor and perylene tetracarboxylic esters as acceptor. Mesophases of blends were characterized by using polarized optical microscopy, differential scanning calorimetry, and X-ray diffraction. Results suggest that all the blends formed liquid crystalline phases, where both compounds in the blends self-assembled separately into columns yet cooperatively contributed to the overall hexagonal or tetragonal columnar mesophase structure. The charge carrier mobilities were characterized using a time-of-flight technique. The phase-separated columnar nanostructures of the donor and acceptor components play an important role in the formation of molecular heterojunctions exhibiting highly efficient ambipolar charge transport, with mobilities on the order of 10⁻³ cm² V⁻¹ s⁻¹. These blends with ambipolar transport properties have great potential for application in non-fullerene organic solar cells, particularly in bulk heterojunction architectures. Full article