Atomic Pathways Underlying Light-Induced Changes in Organic Solar Cell Materials
Atomic Pathways Underlying Light-Induced Changes in Organic Solar Cell Materials
复制标题
DOI：
10.1021/acs.jpcc.5b05234
复制
发表时间：
2015-08
影响因子：
3.7
通讯作者：
Satvik Shah;R. Biswas
中科院分区：
文献类型：
--
作者：
Satvik Shah;R. Biswas
We identify atomic pathways, involving local O and H motion, which underlie intrinsic light-induced changes of organic materials, utilizing ab initio simulations. Light exposure generates prolonged intrinsic degradation of organic solar cells, when moisture and oxygen are absent. We consider the polymer PTB7, common for higher efficiency cells. Local motion of O from the C–O–C bridge to a C═O bond in the aromatic backbone, creates a C-dangling bond defect, with an energy of 2.1 eV. The energy barrier of ≤2.65 eV can be surmounted with blue photons. Local H motion from βC to αC within the alkyl, also generates a C-dangling bond, a similar rebonding of bridging-O, and cleaving of PTB7. Bridging O creates instability. Defect energies are lowered by ∼0.5 eV by excited electronic states. Defects can anneal reversibly or irreversibly to distorted configurations. We identify why certain organic materials are more stable, and pathways to design more stable materials.
