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Updated: Oct 13, 2025
08:29
Morphology Control for Fully Printable Organic–Inorganic Bulk-heterojunction Solar Cells Based on a Ti-alkoxide and Semiconducting Polymer
Published on: January 10, 2017
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Evidence That Sharp Interfaces Suppress Recombination in Thick Organic Solar Cells
Obaid Alqahtani1,2, Seyed Mehrdad Hosseini3, Thomas Ferron4
1Materials Science and Engineering Program, Washington State University, Pullman, Washington 99164, United States.
ACS Applied Materials & Interfaces
|November 17, 2021
Summary
Thick organic solar cells (OSCs) need optimized nanomorphology for efficient charge collection. Sharp interfaces between donor and acceptor domains are crucial for suppressing charge recombination and enabling high performance in printed OSCs.
Area of Science:
- Materials Science
- Organic Electronics
- Photovoltaics
Background:
- Commercializing organic solar cells (OSCs) requires thick active layers (>400 nm) for high performance using industrial printing.
- Achieving this thickness with high efficiency is challenging for non-fullerene acceptor (NFA) OSCs.
- The NT812/PC71BM system shows performance increases with thickness due to suppressed charge recombination, but this suppression is processing-dependent.
Purpose of the Study:
- To investigate the morphological origins of suppressed charge recombination in thick active-layer OSCs.
- To understand how nanomorphology influences charge collection efficiency in printed organic solar cells.
- To establish structure-property relationships for optimizing NFA OSCs.
Main Methods:
- Utilized a suite of X-ray techniques to analyze the nanomorphology of organic solar cell active layers.
- Investigated the correlation between nanodomain aggregation, interfacial characteristics, and charge recombination.
- Quantitatively studied the donor/acceptor interfacial width in relation to charge recombination.
Main Results:
- Despite similar aggregated nanodomains across devices, charge recombination (Langevin reduction factor) varied significantly (∼2 to >1000).
- Pure aggregated phases alone are insufficient to explain reduced recombination.
- Large, well-ordered conduits and sharp donor/acceptor interfaces were identified as key factors for charge separation and collection in thick films.
Conclusions:
- Nanomorphology, specifically sharp interfaces and ordered conduits, plays a critical role in suppressing charge recombination in thick NFA OSCs.
- This study provides the first quantitative link between interfacial width and non-Langevin recombination.
- The identified structure-property relationships are vital for the commercialization and scale-up of printed organic solar cells.
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