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Organic solar cells (OSCs) have emerged as promising candidates for renewable energy harvesting due to their lightweight, flexible, and low‐cost fabrication potential. The efficiency of OSCs is largely determined by the choice of solvents, which significantly affect the film morphology of the active layers, the intermixed donor‐acceptor domains, and overall device performance. Beginning with an introduction to the importance of solvent selection, the screening and classification of solvents, emphasizing their characteristics and classification based on sustainability, solubility, and other additional considerations are explored. Various non‐halogenated solvents, highlighting commonly used aromatic solvents, biomass‐derived solvents, and water/alcohol‐based solvents are explored. The state‐of‐the‐art donor and acceptor materials, focusing on efficient donor materials such as PM6 and D18, and high‐performing Y‐series acceptors are also presented. Strategies for developing high‐performance OSCs processed using non‐halogenated solvents are examined, including solvent engineering with additive and additive‐free approaches, ternary strategies, and layer‐by‐layer techniques. The fabrication of large‐area devices using non‐halogenated solvents is addressed, focusing on blade‐coating, slot‐coating, and other processing techniques. Finally, this review outlines future research directions in the non‐halogenated solvent processing of OSCs, emphasizing the need for continuous innovation to overcome existing limitations and propel OSC technology toward commercial viability. [ABSTRACT FROM AUTHOR]

Organic solar cells (OSCs) are a promising photovoltaic technology that employs organic semiconductor material as the photoactive layer, which has the unique advantages of light weight, large‐area flexible fabrication, low‐cost, and semitransparent. In recent years, the performance of OSCs has been significantly improved, and the highest power conversion efficiency has exceeded 19%. Despite the tremendous progress in OSCs, the major bottleneck in realizing the commercialization of OSCs is the device stability. Therefore, reviewing the recent research progress on the stability of high‐performance OSCs is urgent and necessary. This review discusses the factors limiting device lifetime, such as metastable morphology, air, irradiation, heat, and mechanical stresses. Additionally, this review presents the research progress over the last 5 years, focusing on enhancing device stability from the perspective of photoactive layers and other functional layers, which includes material design and device engineering, such as solid additives, device fabrication, optimizing buffer layers, using stable electrodes, and encapsulation. Lastly, this review explores current commercialization challenges and prospects, including using advanced machine learning techniques to assist experimental research. [ABSTRACT FROM AUTHOR]

Dye-sensitized solar cells (DSSCs) have attracted significant interest in the scientific community in recent years due to their advantages such as low fabrication cost, facile fabrication and capability to increase the DSSC performance. Up to date, there are a lot of efforts that have been performed to enhance the DSSC performance by introducing compact layers (CLs) and light scattering layer (LSLs) at the TiO 2 photoactive layer. The CLs can reduce the recombination effect by preventing direct contact between transparent conductive oxide substrates and redox electrolytes. The CLs can reduce current leakage and generate more photocurrent and voltage, resulting in high DSSC performance. The performance of DSSCs also can be improved via the addition of LSLs. The LSLs must be larger than the titanium dioxide (TiO 2) nanoparticles (typical photoanode in DSSCs) to trap more incident light and can excite more electrons, producing high power conversion efficiency. This review will be focused on the modification of the TiO 2 photoactive layer by introducing CLs and LSLs to reduce the recombination effect and increase the light scattering effect for enhancing the DSSC performance. This review highlights various approaches and morphologies to prepare the CLs and LSLs using metal oxides and carbon-based materials. [ABSTRACT FROM AUTHOR]

Polymer solar cells (PSCs) generally suffer energy losses due to low efficient exciton separation and carrier transfer within the active layer. In this paper, adding SnO 2 nanoparticles (SNs) directly into the photoactive layer is proposed for reducing electron-hole recombination and thus facilitating electron transfer across the active layer. It is found that SN addition with appropriate amount can evidently enhance device performance with the power conversion efficiency from 2.67% to 3.39% mainly owing to the improved photocurrent density and fill factor. A systematic investigation confirms that the enhanced exciton separation and carrier transfer in the photoactive layer indeed plays the key role for performance improvement of the devices with appropriate SN addition. This work thus provides a simple strategy of reconciling the contradiction of effective carrier collection and efficient light absorption and thus improving the performance of PSCs. Image 1 • Adding SnO 2 nanoparticles into the photoactive layer can improve the performance of a polymer solar cell. • 27.0% increment of power conversion efficiency is achieved for the optimal device. • The added SnO 2 facilatates exciton separation, carrier transfer and collection. [ABSTRACT FROM AUTHOR]

Fullerene, C 60 photosensitizer was incorporated into poly(Azure A) in the process of electrochemical polymerization from the solution of corresponding dye and fullerene. The synthesized organic layer (PAA_C 60 /ITO) was characterized by means of cyclic voltammetry, UV–Vis, Raman and X-ray photoelectron spectroscopies. It was shown that PAA_C 60 /ITO exhibits strong absorption in both UV and Vis regions and that both immobilized photosensitizers, i.e. Azure A and C 60 , retain their photochemical activity towards 1 O 2 generation under illumination as tested with 2,3,4,5-tetraphenylcyclopentadienone (TPCPD) singlet oxygen quencher. The electrodeposited photoactive layer composed of two photosensitizers was investigated as a source of 1 O 2 in the process of α-terpinene oxidation. [ABSTRACT FROM AUTHOR]

Metal phthalocyanine layers were formed on ITO in a process of electrochemical deposition from a solution of a metal (tetraamino)phthalocyanine (MPcNH 2). Three MPcNH 2 were investigated: with Zn, Al or Cu as a central metal atom. The chemical structure and properties of the electrodeposited photoactive layers, (MPcNH 2) layer , were widely-characterized by UV–Vis, infrared (ATR-IR), Raman and X-ray photoelectron (XPS) spectroscopies and scanning electron (SEM) and atomic force microscopies (AFM). The photochemical activity towards generation of singlet oxygen or other reactive oxygen species was investigated applying indirect method with 1,3-diphenylisobenzofuran (DPBF) or α-terpinene as a chemical trap. It was shown that while the outer primary amino group governs the electrodeposition process, the properties of the resulting layers depends mainly on the type of central metal atom. • Metal phthalocyanines containing outer –NH 2 groups were electrodeposited on ITO. • Presence of –NH 2 induces aniline-like mechanism of electrodeposition. • Effectiveness of electrodeposition process depends on central metal. • All layers (Cu-, Al-, Zn-) were able to produce reactive oxygen species (ROS). • Layers with Zn- and Al-phthalocyanines were able to photogenerate singlet oxygen. [ABSTRACT FROM AUTHOR]

Microcavity organic solar cells (OSCs) consisting of different photoactive layers were systematically investigated to demonstrate the potential of using this strategy for efficient light-harvesting. The device structure was carefully optimized to achieve maximal photocurrent (J max) through optical simulation based on transfer matrix method. The results showed that by replacing ITO with ZnO/Ag/ZnO multilayer structure as transparent electrode on the glass substrate, the microcavity OSCs exhibited lower J max compared to the ITO-based devices for the active layers with absorption spectra beyond 800 nm. Optical properties within the device indicated that the decrease of the J max was ascribed to the lower transmittance of ultrathin metal film, which offset the improved absorption of low energy photons near the band edge of the photoactive layers by the microcavity light-trapping effects. Based on these results, top-illuminated microcavity configuration was designed for the ultra-narrow bandgap bulk heterojunction (BHJ) systems, which allowed a significant increase of the J max , reaching the values as high as those of devices built on ITO-coated substrates. Our results can provide a guideline for the further optimization of microcavity effect, especially for the highly efficient nonfullerene BHJs with strong near-infrared (NIR) absorptions to facilitate the fabrication of high-performance large-area flexible OSC devices. • Microcavity can enhance light absorption near the band edge of photoactive layers. • Bottom-illuminated structure is not suitable for ultra-narrow bandgap active layers. • Low transmittance of ZnO/Ag/ZnO is limiting factor in bottom-illuminated devices. • Top-illuminated microcavity exhibit higher photocurrent for near-infrared absorbers. [ABSTRACT FROM AUTHOR]

• Photoactive layers containing C 60 dyads as photosensitizer were electrodeposited. • Deposited layers were able to generate 1O 2 when activated by visible light. • Photoactive properties of layers were optimized by varying monomers ratio. A selenophene-containing fullerene dyad (C 60 Se) was electrochemically co-deposited with bis-selenophene (BisSe) to form a visible light absorbing poly(selenophene) layer with incorporated fullerene photosensitizers on platinum (Pt) or indium-tin oxide (ITO) substrates. The resulting photoactive films (P(C 60 Se_BisSe)) were characterized by cyclic voltammetry, UV–Vis, IR, Raman and X-ray photoelectron spectroscopies. The efficiency of P(C 60 Se_BisSe) towards singlet oxygen photogeneration was investigated by applying reactions with chemical traps, i.e. α-terpinene and 1,3–diphenylisobenzofuran (DPBF), monitored by UV–Vis spectroscopy. The composition of the electropolymerized layer was controlled by varying the monomers ratio in the feed solution and it had a strong influence on the spectroscopic and photosensitizing properties of the deposited film. It has been shown that the efficiency of the visible light-driven singlet oxygen generation can be increased by optimizing the ratio between C 60 photosensitizers and organic units in the layer. [ABSTRACT FROM AUTHOR]

Although high power conversion efficiency of over 14% has been achieved using nonfullerene acceptors (NFAs) in organic photovoltaics (OPVs), securing their insensitive device performance to the thickness of the photoactive layer remains an indispensable requirement for their successful commercialization via printing technologies. In this study, by synthesizing a new series of ITIC‐based NFAs having alkyl or alkoxy groups, it is found that the bulk heterojunction morphology dependence on the thickness of the photoactive layer becomes more severe as the difference in the surface energy of the donor and acceptor increases. It is believed that this observation is the origin that yields the device performance dependence on the thickness of the photoactive layer. Through sensitive control of the surface energy of these ITIC‐based NFAs, it is demonstrated that thickness‐insensitive OPVs can be achieved even using a doctor blade technique under air without using any additives. It is believed that present approach provides an important insight into the design of photoactive materials and morphology control for the printable OPVs using NFAs. The difference in the surface energy of the donor and acceptor is the origin to determine the sensitivity of bulk heterojunction morphology to the thickness of a photoactive layer. By delicately controlling the surface energy of nonfullerene acceptors via side chain engineering, thickness‐insensitive organic photovoltaics are demonstrated using a doctor blade technique under air without using any additives. [ABSTRACT FROM AUTHOR]

Bulk-heterojunction organic solar cells (OSCs) have received considerable attention with significant progress recently and offer a promising outlook for portable energy resources and building-integrated photovoltaics in the future. Now, it is urgent to promote the research of OSCs toward their commercialization. For the commercial application of OSCs, it is of great importance to develop high performance, high stability, and low cost photovoltaic materials. In this review, a comprehensive overview of the fundamental requirements of photoactive layer materials and interface layer materials toward commercialization is provided, mainly focusing on high performance, green manufacturing, simplifying device fabrication processes, stability, and cost issues. Furthermore, the perspectives and opportunities for this emerging field of materials science and engineering are also discussed., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Organic photovoltaics (OPVs) have been pursued as a next generation power source due to their light weight, thin, flexible, and simple fabrication advantages. Improvements in OPV efficiency have attracted great attention in the past decade. Because the functional layers in OPVs can be dissolved in common solvents, they can be manufactured by eco-friendly and scalable printing or coating technologies. In this review article, the focus is on recent efforts to control nanomorphologies of photoactive layer and discussion of various solution-processed charge transport and extraction materials, to maximize the performance of OPV cells. Next, recent works on printing and coating technologies for OPVs to realize solution processing are reviewed. The review concludes with a discussion of recent advances in the development of non-traditional lamination and transfer method towards highly efficient and fully solution-processed OPV., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)