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Reliability of Small Molecule Organic Photovoltaics with Electron‐Filtering Compound Buffer Layers
Author(s) -
Burlingame Quinn,
Song Byeongseop,
Ciammaruchi Laura,
Zanotti Gloria,
Hankett Jeanne,
Chen Zhan,
Katz Eugene A.,
Forrest Stephen R.
Publication year - 2016
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201601094
Subject(s) - materials science , organic solar cell , photovoltaic system , degradation (telecommunications) , energy conversion efficiency , band gap , optoelectronics , photovoltaics , solar cell , chemical engineering , polymer , electrical engineering , engineering , composite material
Electron‐filtering compound buffer layers (EF‐CBLs) improve charge extraction in organic photovoltaic cells (OPVs) by blending an electron‐conducting fullerene with a wide energy gap exciton‐blocking molecule. It is found that devices with EF‐CBLs with high glass transition temperatures and a low crystallization rate produce highly stable morphologies and devices. The most stable OPVs employ 1:1 2,2′,2″‐(1,3,5‐benzenetriyl tris ‐[1‐phenyl‐1 H ‐benzimidazole] TPBi:C 70 buffers that lose <20% of their initial power conversion efficiency of 6.6 ± 0.6% after 2700 h under continuous simulated AM1.5G illumination, and show no significant degradation after 100 days of outdoor aging. When exposed to 100‐sun (100 kW m −2 ) concentrated solar illumination for 5 h, their power conversion efficiencies decrease by <8%. Moreover, it is found that the reliability of the devices employing stable EF‐CBLs has either reduced or no dependence on operating temperature up to 130 °C compared with BPhen:C 60 devices whose fill factors show thermally activated degradation. The robustness of TPBi:C 70 devices under extreme aging conditions including outdoor exposure, high temperature, and concentrated illumination is promising for the future of OPV as a stable solar cell technology.