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Carbon Dangling Bonds in Photodegraded Polymer:Fullerene Solar Cells

Unattached, dangling carbon bonds have been shown experimentally to be the main culprit in degradation of polymer solar cells.  This type of solar cell has attracted intense attention due to their potential for use in flexible large-area, low-cost photovoltaic panels; degradation is the primary obstacle to commercialization.  Theoretical studies suggested photo-induced carbon-hydrogen bond rearrangement and breaking can lead to carbon dangling bonds and now this has been shown experimentally for the first time.  Researchers studied polymer:fullerene solar cells using the technique electron paramagnetic resonance, which fingerprinted the dangling bonds when blue and shorter wavelength light was shone on the samples.  The dangling bonds were demonstrated to form at polymer:fullerene interfaces.  Importantly, the carbon dangling bonds decay over a period of several weeks at room temperature in the dark in a process yet to be determined and the performance of the solar cell does not return.  This research provides a path to figuring out how to prevent polymer solar cell degradation.Unattached, dangling carbon bonds have been shown experimentally to be the main culprit in degradation of polymer solar cells.  This type of solar cell has attracted intense attention due to their potential for use in flexible large-area, low-cost photovoltaic panels; degradation is the primary obstacle to commercialization.  Theoretical studies suggested photo-induced carbon-hydrogen bond rearrangement and breaking can lead to carbon dangling bonds and now this has been shown experimentally for the first time.  Researchers studied polymer:fullerene solar cells using the technique electron paramagnetic resonance, which fingerprinted the dangling bonds when blue and shorter wavelength light was shone on the samples.  The dangling bonds were demonstrated to form at polymer:fullerene interfaces.  Importantly, the carbon dangling bonds decay over a period of several weeks at room temperature in the dark in a process yet to be determined and the performance of the solar cell does not return.  This research provides a path to figuring out how to prevent polymer solar cell degradation.

Schematic showing the probable location of the carbon dangling bonds via EPR and electronic measurements.

Highlight Date: 
Monday, March 27, 2017
Author(s): 
Fadzai Fungara, William R. Lindemann, Joseph Shinar, and Ruth Shinar
Article Link: 
Journal Name: 
Advanced Energy Materials
Volume: 
7
Year: 
2017
Page Number(s): 
1601420
Project Affiliation: