Enhanced Charge Separation Efficiency in DNA Templated Polymer Solar Cells |
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Authors: | Francesco Toschi Daniele Catone Patrick O'Keeffe Alessandra Paladini Stefano Turchini Janardan Dagar Thomas M. Brown |
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Affiliation: | 1. Istituto di Struttura della Materia‐CNR (ISM‐CNR), Division of Ultrafast Processes in Materials (FLASHit), 00015 Monterotondo, Italy;2. Istituto di Struttura della Materia‐CNR (ISM‐CNR), Division of Ultrafast Processes in Materials (FLASHit), Area della Ricerca di Roma Tor Vergata, Rome, Italy;3. CHOSE (Centre for Hybrid and Organic Solar Energy), Department of Electronic Engineering, University of Rome Tor Vergata, Rome, Italy |
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Abstract: | The insertion of a DNA nanolayer into polymer based solar cells, between the electron transport layer (ETL) and the active material, is proposed to improve the charge separation efficiency. Complete bulk heterojunction donor–acceptor solar cells of the layered type glass/electrode (indium tin oxide)/ETL/P3HT:PC70BM/hole transport layer/electrode (Ag) are investigated using femtosecond transient absorption spectroscopy both in the NIR and the UV–vis regions of the spectrum. The transient spectral changes indicate that when the DNA is deposited on the ZnO nanoparticles (ZnO‐NPs) it can imprint a different long range order on the poly(3‐hexylthiophene) (P3HT) polymer with respect to the non‐ZnO‐NPs/DNA containing cells. This leads to a larger delocalization of the initially formed exciton and its faster quenching which is attributed to more efficient exciton dissociation. Finally, the temporal response of the NIR absorption shows that the DNA promotes more efficient production of charge transfer states and free polarons in the P3HT cation indicating that the increased exciton dissociation correlates with increased charge separation. |
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Keywords: | charge separation DNA exciton dissociation polymer based bulk heterojunction solar cells ultrafast transient absorption |
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