Photocrosslinkable bromine-functionalized poly(3-hexylthiophene) (P3HT-Br) copolymers designed for application in solution-processed organic photovoltaics are prepared by copolymerization of 2-bromo-3-(6-bromohexyl) thiophene and 2-bromo-3-hexylthiophene. The monomer ratio is carefully controlled to achieve a UV photocrosslinkable layer while retaining the π–π stacking feature of the conjugated polymers. The new materials are used as electron donors in both bulk heterojunction (BHJ) and bilayer type photovoltaic devices. Unlike devices prepared from either P3HT:PCBM blend or P3HT-Br:PCBM blend without UV treatment, photocrosslinked P3HT-Br:PCBM devices are stable even when annealed for two days at the elevated temperature of 150 °C as the nanophase separated morphology of the bulk heterojunction is stabilized as confirmed by optical microscopy and grazing incidence wide angle X-ray scattering (GIWAXS). When applied to solution-processed bilayer devices, the photocrosslinkable materials show high power conversion efficiencies (∼2%) and excellent thermal stability (3 days at 150 °C). Such performance, one of the highest obtained for a bilayer device fabricated by solution processing, is achieved as crosslinking does not disturb the π–π stacking of the polymer as confirmed by GIWAXS measurements. These novel photocrosslinkable materials provide ready access to efficient bilayer devices thus enabling the fundamental study of photophysical characteristics, charge generation, and transport across a well-defined interface.

http://absimage.aps.org/image/MAR09/MWS_MAR09-2008-000095.pdf

Photo-crosslinkable Polythiophenes for Efficient Thermally Stable Organic Photovoltaics

Recent interest in flexible electronics has led to a paradigm shift in consumer electronics, and the emergent development of stretchable and wearable electronics is opening a new spectrum of ubiquitous applications for electronics. Organic electronic materials, such as π-conjugated small molecules and polymers, are highly suitable for use in low-cost wearable electronic devices, and their charge-carrier mobilities have now exceeded that of amorphous silicon. However, their commercialization is minimal, mainly because of weaknesses in terms of operational stability, long-term stability under ambient conditions, and chemical stability related to fabrication processes. Recently, however, many attempts have been made to overcome such instabilities of organic electronic materials. Here, an overview is provided of the strategies developed for environmentally robust organic electronics to overcome the detrimental effects of various critical factors such as oxygen, water, chemicals, heat, and light. Additionally, molecular design approaches to π-conjugated small molecules and polymers that are highly stable under ambient and harsh conditions are explored; such materials will circumvent the need for encapsulation and provide a greater degree of freedom using simple solution-based device-fabrication techniques. Applications that are made possible through these strategies are highlighted.

Toward Environmentally Robust Organic Electronics: Approaches and Applications.

The adsorption, desorption, co-adsorption, and exchange behavior of phosphonic acid, carboxylic acid, and catechol derivatives on the surface of titanium oxide (anatase) nanoparticles are investigated. Thermogravimetric analysis provides a facile and fast-track quantitative determination of the wet-chemical monolayer adsorption constants and grafting densities of ten adsorbates, all under neutral pH conditions. This characterization protocol allows straightforward quantification of the relevant thermodynamic data of ligand adsorption and a comparison of ligand adsorption strengths. The reported procedure is proposed as a universal tool and it should be applicable to many other colloidal metal oxide materials. Moreover, the determined values for the adsorption constants and the monolayer grafting densities provide a toolbox for the assessment of the adsorbates’ behavior in desorption, exchange, and co-adsorption equilibria. This versatile evaluation procedure will help to identify optimal monolayer–surface combinations and to evaluate critical parameters, such as monolayer robustness, ligand exchange rates, or targeted mixed assembly of functionalities.

Quantitative Determination and Comparison of the Surface Binding of Phosphonic Acid, Carboxylic Acid, and Catechol Ligands on TiO2 Nanoparticles

Organic solar cells (OSCs) have achieved much attention and meanwhile reach efficiencies above 10% One problem yet to be solved is the lack of long term stability Crosslinking is presented as a tool to increase the stability of OSCs A number of materials used for the crosslinking of bulk heterojunction cells are presented These include the crosslinking of low bandgap polymers used as donors in bulk heterojunction cells, as well as the crosslinking of fullerene acceptors and crosslinking between donor and acceptor External crosslinkers often based on multifunctional azides are also discussed In the second part, some work either leading to OSCs with high efficiencies or giving insight into the chemistry and physics of crosslinking are highlighted The diffusion of low molar mass fullerenes in a crosslinked matrix of a conjugated polymer and the influence of crosslinking on the carrier mobility is discussed Finally, the use of crosslinking to make stable interlayers and the solution processing of multilayer OSCs are discussed in addition to presentation of a novel approach to stabilize nanoimprinted patterns for OSCs by crosslinking

https://www.onlinelibrary.wiley.com/doi/pdf/10.1002/aenm.201700306

Crosslinked Semiconductor Polymers for Photovoltaic Applications

Thank you very much for downloading handbook of photovoltaic science and engineering. Maybe you have knowledge that, people have search numerous times for their favorite books like this handbook of photovoltaic science and engineering, but end up in infectious downloads. Rather than reading a good book with a cup of tea in the afternoon, instead they cope with some malicious virus inside their desktop computer.

Handbook Of Photovoltaic Science And Engineering

A critical issue of bulk heterojunction (BHJ) solar cells is the instability of the morphology of the polymer:fullerene blend over long operation times. We report the synthesis of crosslinkable derivatives of the low bandgap polymer PFDTBT, poly(2,7-(9,9-dialkylfluorene)-alt-(5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole))), and the stabilization of BHJ solar cells by crosslinking. Oxetane units are attached to the polymer side chains as crosslinkable functional groups. We study the crosslinking of the polymers via cationic ring opening polymerization of the oxetanes and show that our materials rapidly form insoluble networks. Our materials also crosslink in the presence of fullerenes. We report for the first time that crosslinking takes place upon prolonged heating to 100 °C without any added initiator. The best efficiency and thermal stability are found in thermally crosslinked BHJ solar cells. After 30 hours at 100 °C, 65% of the initial efficiency are retained and no further decay is observed up to 100 hours.

Initiator-free crosslinking of oxetane functionalized low bandgap polymers: an approach towards stabilized bulk heterojunction solar cells

We present a number of polyfluorene based conjugated polymers with crosslinkable acrylate and oxetane units. These polymers can be crosslinked by free radical polymerization in the case of acrylates and by cationic ring opening polymerization for oxetanes. Upon polymerization densely crosslinked networks are formed which are completely insoluble. We show that the diffusion coefficient of C60 in polyfluorene is reduced by a factor of 1000 by crosslinking. MIS-CELIV measurements are used to monitor changes in the charge carrier mobility upon crosslinking. It shows that using appropriate conditions, e.g. low initiator concentrations or thermal crosslinking, the charge carrier mobility is not reduced by crosslinking. Solution processed three layer organic solar cells were realized with a crosslinkable fluorene based copolymer containing acrylate groups. The efficiency is increased from 1.4% for the reference to 1.8% in the three layer cell with a crosslinked exciton blocking layer. A critical issue of BHJ cells is the instability of the morphology of the polymer:fullerene blend over long operation times at elevated temperature. We present a crosslinkable derivative of the low bandgap polymer PFDTBT which contains oxetane units. BHJ cells with the crosslinked PFDTBT derivative and PCBM were tested in accelerated aging experiments at 100 °C for times up to 100 h. Stabilization was clearly observed in crosslinked BHJ cells compared to the non-crosslinked reference. We show for the first time that oxetane containing polymers can be thermally crosslinked without any added initiator. Initiator free crosslinking is particularly attractive as it avoids the formation of decomposition products, and thus potential electron traps and quenching sites from the initiator.

Crosslinkable low bandgap polymers for organic solar cells

Photocrosslinking is known as a suitable method for patterning organic semiconductors in organic light emitting diodes. We extend this concept to the field of organic solar cells using conjugated polymers bearing sidechains with photocrosslinkable oxetane units. By UV irradiation in the presence of a photo acid generator the oxetane groups polymerize, leading to the formation of a densely crosslinked, and thus insoluble, network of a low-bandgap polymer. In this paper we present the synthesis of two novel photocrosslinkable low-bandgap polymers PFDTBTOx and PCDTBTOx and discuss several strategies for the fabrication of organic solar cells taking advantage of the novel crosslinkable materials.

Patternable conjugated polymers for organic solar cells

The thermal stability and molecular order in monolayers of two organic semiconductors, PBI-PA and PBI-alkyl, based on perylene derivatives with an identical molecular structure except for an anchor group for attachment to the substrate in PBI-PA, are reported. In situ X-ray reflectivity measurements are used to follow the stability of these monolayers in terms of order and thickness as temperature is increased. Films have thicknesses corresponding approximately to the length of one molecule; molecules stand upright on the substrate with a defined structure. PBI-PA monolayers have a high degree of order at room temperature and a stable film exists up to 250 °C, but decomposes rapidly above 300 °C. In contrast, stable physisorbed PBI-alkyl monolayers only exist up to 100 °C. Above the bulk melting point at 200 °C no more order exists. The results encourage using anchor groups in monolayers for various applications as it allows enhanced stability at the interface with the substrate.

Thermal stability and molecular ordering of organic semiconductor monolayers: effect of an anchor group.

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Philipp Knauer

Author Tools

Chat about Author

Papers

Initiator-free crosslinking of oxetane functionalized low bandgap polymers: an approach towards stabilized bulk heterojunction solar cells

Crosslinkable low bandgap polymers for organic solar cells

Patternable conjugated polymers for organic solar cells

Thermal stability and molecular ordering of organic semiconductor monolayers: effect of an anchor group.