Tailored exciton diffusion in organic photovoltaic cells for enhanced power conversion efficiency
- 11 November 2012
- journal article
- Published by Springer Science and Business Media LLC in Nature Materials
- Vol. 12 (2), 152-157
- https://doi.org/10.1038/nmat3467
Abstract
Photoconversion in planar-heterojunction organic photovoltaic cells (OPVs) is limited by a short exciton diffusion length (L(D)) that restricts migration to the dissociating electron donor/acceptor interface. Consequently, bulk heterojunctions are often used to realize high efficiency as these structures reduce the distance an exciton must travel to be dissociated. Here, we present an alternative approach that seeks to directly engineer L(D) by optimizing the intermolecular separation and consequently, the photophysical parameters responsible for excitonic energy transfer. By diluting the electron donor boron subphthalocyanine chloride into a wide-energy-gap host material, we optimize the degree of interaction between donor molecules and observe a ~50% increase in L(D). Using this approach, we construct planar-heterojunction OPVs with a power conversion efficiency of (4.4 ± 0.3)%, > 30% larger than the case of optimized devices containing an undiluted donor layer. The underlying correlation between L(D) and the degree of molecular interaction has wide implications for the design of both OPV active materials and device architectures.Keywords
This publication has 40 references indexed in Scilit:
- Solution-processed small-molecule solar cells with 6.7% efficiencyNature Materials, 2011
- Arylamine-Based Squaraine Donors for Use in Organic Solar CellsNano Letters, 2011
- Simultaneous Enhancement of Open‐Circuit Voltage, Short‐Circuit Current Density, and Fill Factor in Polymer Solar CellsAdvanced Materials, 2011
- Dicyanovinyl–Substituted Oligothiophenes: Structure‐Property Relationships and Application in Vacuum‐Processed Small Molecule Organic Solar CellsAdvanced Functional Materials, 2011
- For the Bright Future—Bulk Heterojunction Polymer Solar Cells with Power Conversion Efficiency of 7.4%Advanced Materials, 2010
- Efficient bulk heterojunction photovoltaic cells using small-molecular-weight organic thin filmsNature, 2003
- Excitonic Solar CellsThe Journal of Physical Chemistry B, 2003
- Polymer Photovoltaic Cells: Enhanced Efficiencies via a Network of Internal Donor-Acceptor HeterojunctionsScience, 1995
- Efficient photodiodes from interpenetrating polymer networksNature, 1995
- Two-layer organic photovoltaic cellApplied Physics Letters, 1986