A Top‐Down Strategy to Engineer ActiveLayer Morphology for Highly Efficient and Stable All‐Polymer Solar Cells
Abstract
A major challenge hindering the further development of all‐polymer solar cells (all‐PSCs) employing polymerized small‐molecule acceptors is the relatively low fill factor (FF) due to the difficulty in controlling the active‐layer morphology. The issues typically arise from oversized phase separation resulting from the thermodynamically unfavorable mixing between two macromolecular species, and disordered molecular orientation/packing of highly anisotropic polymer chains. Herein, a facile top‐down controlling strategy to engineer the morphology of all‐polymer blends is developed by leveraging the layer‐by‐layer (LBL) deposition. Optimal intermixing of polymer components can be achieved in the two‐step process by tuning the bottom‐layer polymer swelling during top‐layer deposition. Consequently, both the molecular orientation/packing of the bottom layer and the molecular ordering of the top layer can be optimized with a suitable top‐layer processing solvent. A favorable morphology with gradient vertical composition distribution for efficient charge transport and extraction is therefore realized, affording a high all‐PSC efficiency of 17.0% with a FF of 76.1%. The derived devices also possess excellent long‐term thermal stability and can retain >90% of their initial efficiencies after being annealed at 65 °C for 1300 h. These results validate the distinct advantages of employing an LBL processing protocol to fabricate high‐performance all‐PSCs.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jul 15, 2022
- Source ID
- 10.1002/adma.202202608
Entities
People
- Alex Jen
- Baobing Fan
- Francis Lin
- Guanghao Lu
- Han Young Woo
- Harald Ade
- Huiting Fu
- Kui Jiang
- Qi Feng
- Qunping Fan
- Yixin Ran
- Zhengxing Peng
- Ziang Wu
Organizations
- Cancer Research Foundation
- City University of Hong Kong
- Glaucoma Research Foundation
- Korea University
- National Research Foundation of Korea
- North Carolina State University
- Office of Basic Energy Sciences
- Office of Naval Research
- Office of Science
- United States Department of Energy
- University of Washington