Bulk heterojunction (BHJ) organic solar cells (OSCs), prepared by blending an electron donor and electron acceptor, have attracted considerable attention due to their potential flexibility, low cost, and the possibility of large area roll-to-roll (R2R) fabrication. Owig to the extensive investigation of active donor and acceptor materials, the power conversion efficiency (PCE) has been significantly increased from around 1% in 1986 to, more recently, 13%. In addition to the fine optimization of both active materials, interlayers are also known to play a significant role in PCE by improving the fill factor (FF) parameters. Our previous work has proven that the hydrophilic oligo-oxyethylene chain substitution on the diphenylamine block rigidified the molecule showing better planarity, induced molecular self-organization with mechanofluorochromical and non-linear optical properties due to the counter-acting forces, namely, dipole interactions which favor head-to-tail molecular packing and hydrophilic/lipophilic interactions which in contrast promote co-facial arrangement.
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