Kutsarov, Dimitar I., Rašović, Ilija, Zachariadis, Alexandros, Laskarakis, Argiris, Lebedeva, Maria A., Porfyrakis, Kyriakos ORCID: https://orcid.org/0000-0003-1364-0261, Mills, Christopher A., Beliatis, Michail J., Fisher, Brett, Bruchlos, Kirsten, Ludwigs, Sabine, Logothetidis, Stergios and Silva, S. Ravi P. (2016) Achieving 6.7% efficiency in P3HT/Indene-C70 bisadduct solar cells through the control of vertical volume fraction distribution and optimized regio-isomer ratios. Advanced Electronic Materials, 2 (12):1600362. ISSN 2199-160X (Online) (doi:10.1002/aelm.201600362)

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Abstract

Indene C60 and C70 bisadducts (IC60BA and IC70BA) have relatively high lowest unoccupied molecular orbital energies. In poly(3‐hexylthiophene) (P3HT)‐based polymer solar cells (PSCs), this produces an increase in open‐circuit voltage (VOC) and power conversion efficiency (PCE). However, ICBA synthesis produces a mixture of regio‐isomers with different indene spatial orientations (2, 5, and 12 o'clock) that alter the IC70BA molecular packing when mixed with P3HT. In this paper, how the IC70BA regio‐isomerism affects the PSC performance is examined by investigating the molecular packing of P3HT:IC70BA layers with different regio‐isomeric ratios. For the first time, non‐destructive spectroscopic ellipsometry is used to investigate the effect of the fabrication conditions on the P3HT/IC70BA vertical volume fraction distribution and the results are attributed to the spatial arrangement of the regio‐isomers. It is demonstrated that this unambiguously affects the PSC performance. As a result, record device efficiencies are repeatedly attained for standard architecture P3HT:IC70BA PSCs with photoactive areas of 0.43 cm2, achieving 5.9 (±0.4)% PCE (n = 15). With control of the IC70BA constituent, device PCEs vary from below 2.2% to peak values above 6.7%, among the highest recorded PCEs for a P3HT combination, highlighting the importance of the molecular phase separation for high‐efficiency devices.

Item Type:	Article
Uncontrolled Keywords:	polymer solar cells, high-efficiency, vertical phase separation, regio-isomerism, P3HT-ICBA
Subjects:	T Technology > TK Electrical engineering. Electronics Nuclear engineering
Faculty / School / Research Centre / Research Group:	Faculty of Engineering & Science Faculty of Engineering & Science > School of Engineering (ENG)
Last Modified:	19 Sep 2020 00:20
URI:	http://gala.gre.ac.uk/id/eprint/25774

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