%0 Journal Article %1 AENM:AENM201601420 %A Fungura, Fadzai %A Lindemann, William R. %A Shinar, Joseph %A Shinar, Ruth %D 2016 %J Advanced Energy Materials %K degradation organic traps %P n/a--n/a %R 10.1002/aenm.201601420 %T Carbon Dangling Bonds in Photodegraded Polymer:Fullerene Solar Cells %U http://dx.doi.org/10.1002/aenm.201601420 %X Intrinsic photodegradation of organic solar cells, theoretically attributed to CH bond rearrangement/breaking, remains a key commercialization barrier. This work presents, via dark electron paramagnetic resonance (EPR), the first experimental evidence for metastable C dangling bonds (DBs) formed by blue/UV irradiation of polymer:fullerene blend films in nitrogen. The DB density increases with irradiation and decreases ≈4-fold after 2 weeks in the dark. The dark EPR also shows increased densities of other spin-active sites in photodegraded polymer, fullerene, and polymer:fullerene blend films, consistent with broad electronic measurements of fundamental properties, including defect/gap state densities. The EPR and electronic measurements enable identification of defect states, whether in the polymer, fullerene, or at the donor/acceptor (D/A) interface. Importantly, the EPR results indicate that the DBs are at the D/A interface, as they were present only in the blend films. The role of polarons in interface DB formation is also discussed.

@article{AENM:AENM201601420, abstract = {Intrinsic photodegradation of organic solar cells, theoretically attributed to CH bond rearrangement/breaking, remains a key commercialization barrier. This work presents, via dark electron paramagnetic resonance (EPR), the first experimental evidence for metastable C dangling bonds (DBs) formed by blue/UV irradiation of polymer:fullerene blend films in nitrogen. The DB density increases with irradiation and decreases ≈4-fold after 2 weeks in the dark. The dark EPR also shows increased densities of other spin-active sites in photodegraded polymer, fullerene, and polymer:fullerene blend films, consistent with broad electronic measurements of fundamental properties, including defect/gap state densities. The EPR and electronic measurements enable identification of defect states, whether in the polymer, fullerene, or at the donor/acceptor (D/A) interface. Importantly, the EPR results indicate that the DBs are at the D/A interface, as they were present only in the blend films. The role of polarons in interface DB formation is also discussed.}, added-at = {2016-11-24T11:18:47.000+0100}, author = {Fungura, Fadzai and Lindemann, William R. and Shinar, Joseph and Shinar, Ruth}, biburl = {https://www.bibsonomy.org/bibtex/28039cf23e045c14d8f22e41e98b7f6aa/bretschneider_m}, description = {Carbon Dangling Bonds in Photodegraded Polymer:Fullerene Solar Cells - Fungura - 2016 - Advanced Energy Materials - Wiley Online Library}, doi = {10.1002/aenm.201601420}, interhash = {21050a2111b711ff796a4a155bd6604c}, intrahash = {8039cf23e045c14d8f22e41e98b7f6aa}, issn = {1614-6840}, journal = {Advanced Energy Materials}, keywords = {degradation organic traps}, pages = {n/a--n/a}, timestamp = {2016-11-24T11:18:47.000+0100}, title = {Carbon Dangling Bonds in Photodegraded Polymer:Fullerene Solar Cells}, url = {http://dx.doi.org/10.1002/aenm.201601420}, year = 2016 }