Crosslinkable low bandgap polymers for organic solar cells

Peter Strohriegl; Christina Saller; Philipp Knauer; Anna Köhler; Tobias Hahn; Florian Fischer; Frank-Julian Kahle

doi:10.1117/12.2239400

26 September 2016 Crosslinkable low bandgap polymers for organic solar cells

Peter Strohriegl, Christina Saller, Philipp Knauer, Anna Köhler, Tobias Hahn, Florian Fischer, Frank-Julian Kahle

Proceedings Volume 9942, Organic Photovoltaics XVII; 99420O (2016) https://doi.org/10.1117/12.2239400
Event: SPIE Organic Photonics + Electronics, 2016, San Diego, California, United States

Abstract

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.

Citation Download Citation

Peter Strohriegl, Christina Saller, Philipp Knauer, Anna Köhler, Tobias Hahn, Florian Fischer, and Frank-Julian Kahle "Crosslinkable low bandgap polymers for organic solar cells", Proc. SPIE 9942, Organic Photovoltaics XVII, 99420O (26 September 2016); https://doi.org/10.1117/12.2239400

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available

Members: $17.00

Non-members: $21.00 ADD TO CART

PROCEEDINGS
11 PAGES

DOWNLOAD PAPER SAVE TO MY LIBRARY

GET CITATION

RIGHTS & PERMISSIONS

Get copyright permission Get copyright permission on Copyright Marketplace

KEYWORDS

Polymers

Solar cells

Diffusion

Annealing

Organic photovoltaics

Polymerization

Excitons

Show All Keywords

Keywords/Phrases

Search In:

Publication Years