Triptycene as a supramolecular additive in PTB7:PCBM blends and its influence on photovoltaic properties

Krishnan Jagadamma, L., McCarron, L. J., Wiles, A. A. , Savikhin, V., Sajjad, M., Yazdani, M., Rotello, V. M., Toney, M. F., Cooke, G. and Samuel, I. D. W. (2018) Triptycene as a supramolecular additive in PTB7:PCBM blends and its influence on photovoltaic properties. ACS Applied Materials and Interfaces, 10(29), pp. 24665-24678. (doi:10.1021/acsami.8b03114) (PMID:29932630)

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Abstract

Additives play an important role in modifying the morphology and phase separation of donor and acceptor molecules in bulk heterojunction (BHJ) solar cells. Here we report triptycene (TPC) as a small molecule additive for supramolecular control of phase separation and concomitant improvement of the power conversion efficiency (PCE) of PTB7 donor and fullerene acceptor based BHJ polymer solar cells. An overall 60% improvement in PCE is observed for both PTB7:PC61BM and PTB7:PC71BM blends. The improved PV performance can be attributed to three factors: (a) TPC induced supramolecular interactions with donor:acceptor components in the blends to realise a nanoscale phase separated morphology (b) an increase in the charge transfer (CT) state energy that lowers the driving force for electron transfer from donor to acceptor molecules; and (c) an increase in the charge carrier mobility. An improvement in efficiency using TPC as a supramolecular additive has also been demonstrated for other BHJ blends such as PBDB-T:PC71BM and P3HT:PCBM implying the wide applicability of this new additive molecule. A comparison of the photostability of TPC as an additive for PTB7:PCBM solar cells to that of the widely used 1,8- diiodooctane (DIO) additive shows ~ 30 % higher retention of photovoltaic performance for the TPC-added solar cells after 34 hours of AM 1.5G illumination. The results obtained suggest that the approach of using additives that can promote supramolecular interactions to modify the length scale of phase separation between donor and acceptor is very promising and can lead to the development of highly efficient and stable organic photovoltaics.

Item Type:Articles
Additional Information:We acknowledge support from EPSRC (grant numbers EP/L012294/1 and EP/L012170/1) and the European Research Council (grant number 321305). I. D. W. S. also acknowledges a Royal Society Wolfson Research Merit Award.
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:McCarron, Liam and Cooke, Professor Graeme and Wiles, Dr Alan
Authors: Krishnan Jagadamma, L., McCarron, L. J., Wiles, A. A., Savikhin, V., Sajjad, M., Yazdani, M., Rotello, V. M., Toney, M. F., Cooke, G., and Samuel, I. D. W.
College/School:College of Science and Engineering > School of Chemistry
Journal Name:ACS Applied Materials and Interfaces
Publisher:American Chemical Society
ISSN:1944-8244
ISSN (Online):1944-8252
Published Online:22 June 2018
Copyright Holders:Copyright © 2018 American Chemical Society
First Published:First published in ACS Applied Materials and Interfaces 10(29):24665-24678
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher
Data DOI:10.17630/9a5faed4-4d05-4046-b66d-a5dacebe4d9e

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
605481Self-assembled organic photovoltaic materials.Graeme CookeEngineering and Physical Sciences Research Council (EPSRC)EP/L012170/1CHEM - CHEMISTRY

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