Assessing the stability of high performance solution
processed small molecule solar cells
Cheacharoen, R (Cheacharoen,
Rongrong)[ 1 ] ; Mateker, WR (Mateker,
William R.)[ 1 ] ; Zhang, Q (Zhang, Qian)[ 2 ] ; Kan, B (Kan, Bin)[ 2 ] ; Sarkisian, D (Sarkisian,
Dylan)[ 1 ] ; Liu, XF (Liu, Xiaofeng)[ 3 ] ; Love, JA (Love, John A.)[ 3 ] ; Wan, XJ (Wan, Xiangjian)[ 2 ] ; Chen, YS (Chen,
Yongsheng)[ 2 ] ; Nguyen, TQ (Thuc-Quyen
Nguyen)[ 3 ] ; Bazan, GC (Bazan,
Guillermo C.)[ 3 ] ; McGehee, MD (McGehee,
Michael D.)[ 1 ]
SOLAR ENERGY
MATERIALS AND SOLAR CELLS, 2017, 161: 368-376
DOI: 10.1016/j.solmat.2016.12.021
WOS:000393347000039
Abstract
Solution-processed small molecule-fullerene bulk
heterojunction (SM BHJ) solar cells now have power conversion efficiency (PCE)
greater than 10%. However, degradation of SM BHJ solar cells has not been well
studied. This work reports the first stability study of six high performance
molecules including the record SM BHJ solar cells under device operating
conditions. Solar cells with a range of donor molecular weight from 1200 to
2300 Da giving 6-10% PCE are monitored in nitrogen gas under 1 sun illumination
with maximum power point tracking as well as at 25 degrees C and 70 degrees C
in the dark. Both heat and light contribute to initial exponential decay or
burn-in with total reduction in efficiency from 31% to 66%. Larger molecules
are found to be resistant to heat induced burn-in, while more crystalline
active layers are more resistant to light induced burn-in. After burn-in, the
linear degradation is observed to be governed by thermal processes. Stabilized
TS80 lifetimes of the SM BHJ solar cells range from 3450 h to 5600 h. Molecular
design towards higher stability should aim at increasing thermal stability
while maintaining crystallinity for photostability.
