TY - JOUR
T1 - Achieving 6.7% Efficiency in P3HT/Indene‐C70 Bisadduct Solar Cells through the Control of Vertical Volume Fraction Distribution and Optimized Regio‐Isomer Ratios
AU - Kutsarov, Dimitar
AU - Rasovic, Ilija
AU - Zachariadis, Alexandros
AU - Laskarakis, Argiris
AU - Lebedeva, Maria
AU - Porfyrakis, Kyriakos
AU - Mills, Christopher
AU - Beliatis, Michail
AU - Fisher, Brett
AU - Bruchlos, Kirsten
AU - Ludwigs, Sabine
AU - Logothetidis, Stergios
AU - Silva, S. Ravi P
PY - 2016/12
Y1 - 2016/12
N2 - 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.
AB - 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.
U2 - 10.1002/aelm.201600362
DO - 10.1002/aelm.201600362
M3 - Article
SN - 2199-160X
VL - 2
JO - Advanced Electronic Materials
JF - Advanced Electronic Materials
IS - 12
M1 - 1600362
ER -