Eco-Friendly Polymer Solar Cells: Advances in Green-Solvent Processing and Material Design

Despite the recent breakthroughs of polymer solar cells (PSCs) exhibiting a power conversion efficiency of over 17%, toxic and hazardous organic solvents such as chloroform and chlorobenzene are still commonly used in their fabrication, which impedes the practical application of PSCs. Thus, the development of eco-friendly processing methods suitable for industrial-scale production is now considered an imperative research focus. This Review provides a roadmap for the design of efficient photoactive materials that are compatible with non-halogenated green solvents (e.g., xylenes, toluene, and tetrahydrofuran). We summarize the recent development of green processing solvents and the processing methods to match with the efficient photoactive materials used in non-fullerene solar cells. We further review progress in the use of more eco-friendly solvents (i.e., water or alcohol) for achieving truly sustainable and eco-friendly PSC fabrication. For example, the concept of water- or alcohol-dispersed nanoparticles made of conjugated materials is introduced. Also, recent important progress and strategies to develop water/alcohol-soluble photoactive materials that completely eliminate the use of conventional toxic solvents are discussed. Finally, we provide our perspectives on the challenges facing the current green processing methods and materials, such as large-area coating techniques and long-term stability. We believe this Review will inform the development of PSCs that are truly clean and renewable energy sources.

Biodegradable Materials and Green Processing for Green Electronics

There is little question that the "electronic revolution" of the 20th century has impacted almost every aspect of human life. However, the emergence of solid-state electronics as a ubiquitous feature of an advanced modern society is posing new challenges such as the management of electronic waste (e-waste) that will remain through the 21st century. In addition to developing strategies to manage such e-waste, further challenges can be identified concerning the conservation and recycling of scarce elements, reducing the use of toxic materials and solvents in electronics processing, and lowering energy usage during fabrication methods. In response to these issues, the construction of electronic devices from renewable or biodegradable materials that decompose to harmless by-products is becoming a topic of great interest. Such "green" electronic devices need to be fabricated on industrial scale through low-energy and low-cost methods that involve low/non-toxic functional materials or solvents. This review highlights recent advances in the development of biodegradable materials and processing strategies for electronics with an emphasis on areas where green electronic devices show the greatest promise, including solar cells, organic field-effect transistors, light-emitting diodes, and other electronic devices.

Polyolefin Elastomer as the Anode Interfacial Layer for Improved Mechanical and Air Stabilities in Nonfullerene Solar Cells

Despite the breakthroughs in power conversion efficiency (PCE) values of organic solar cells (OSCs), the other important issue concerns stability, which is urgently needed to be resolved for potential commercialization. A commercial and chemically stable polyolefin elastomer (POE) was incorporated into high-performance PBDB-T:ITIC, PM6:IT-4F, and PM6:Y6 nonfullerene systems to serve as the anode interfacial layer, affording remarkably improved mechanical and air stabilities when compared with those of the most studied MoO₃ interfacial layer. The POE was found to selectively transport holes rather than electrons due to the upshifted surface contact potential of the active layer and the better ohmic contact between the active layer and the electrode. The POE serving as an encapsulating layer is supposed to suppress the penetration of water and oxygen in addition to the diffusion of Ag atoms into the active layer. After storing in an air environment with a humidity of approximately 70% for 150 days, the PCE of the device based on PM6:IT-4F with the POE anode interfacial layer decreased from 11.88 to 9.60%, retaining 80.8% of its original PCE value. The device using MoO₃ as the anode interfacial layer showed a PCE value that was sharply reduced from 12.31 to 2.98% after storing for only 30 days. The POE could be potentially useful for flexible and large-scale device fabrication, accelerating the commercialization of OSCs.

Recent progress in wide bandgap conjugated polymer donors for high-performance nonfullerene organic photovoltaics

This feature article summarizes our recent achievements in the development of wide bandgap polymer donors as high-performance organic photovoltaics.

The effect of aggregation behavior on photovoltaic performances in benzodithiophene-thiazolothiazole-based wide band-gap conjugated polymers with side chain position changes

Two thiazolothiazole-based polymers were designed and synthesized, which exhibited significantly different aggregation and photovoltaic properties.

Achieving efficient polymer solar cells based on benzodithiophene–thiazole-containing wide band gap polymer donors by changing the linkage patterns of two thiazoles

Two conjugated polymers with different combinations of two thiazoles were synthesized to study their photovoltaic performances.