TY  - JOUR
A1  - Jiang, Wei
A1  - Tao, Chen
A1  - Stolterfoht, Martin
A1  - Jin, Hui
A1  - Stephen, Meera
A1  - Lin, Qianqian
A1  - Nagiri, Ravi C. R.
A1  - Burn, Paul L.
A1  - Gentle, Ian R.
T1  - Hole-transporting materials for low donor content organic solar cells
BT  - charge transport and device performance
JF  - Organic electronics : physics, materials and applications
N2  - Low donor content solar cells are an intriguing class of photovoltaic device about which there is still considerable discussion with respect to their mode of operation. We have synthesized a series of triphenylamine-based materials for use in low donor content devices with the electron accepting [6,6]-phenyl-C71-butyric acid methyl ester (PC(7)0BM). The triphenylamine-based materials absorb light in the near UV enabling the PC(7)0BM to be be the main light absorbing organic semiconducting material in the solar cell. It was found that the devices did not operate as classical Schottky junctions but rather photocurrent was generated by hole transfer from the photo-excited PC(7)0BM to the triphenylamine-based donors. We found that replacing the methoxy surface groups with methyl groups on the donor material led to a decrease in hole mobility for the neat films, which was due to the methyl substituted materials having the propensity to aggregate. The thermodynamic drive to aggregate was advantageous for the performance of the low donor content (6 wt%) films. It was found that the 6 wt% donor devices generally gave higher performance than devices containing 50 wt% of the donor.
KW  - photoexcited hole transfer
KW  - photocurrent generation
KW  - synthesis
KW  - hole
KW  - mobility
KW  - low donor content
KW  - Schottky junction
Y1  - 2020
U6  - https://doi.org/10.1016/j.orgel.2019.105480
SN  - 1566-1199
SN  - 1878-5530
VL  - 76
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Perdigon-Toro, Lorena
A1  - Zhang, Huotian
A1  - Markina, Anastaa si
A1  - Yuan, Jun
A1  - Hosseini, Seyed Mehrdad
A1  - Wolff, Christian Michael
A1  - Zuo, Guangzheng
A1  - Stolterfoht, Martin
A1  - Zou, Yingping
A1  - Gao, Feng
A1  - Andrienko, Denis
A1  - Shoaee, Safa
A1  - Neher, Dieter
T1  - Barrierless free charge generation in the high-performance PM6:Y6 bulk heterojunction non-fullerene solar cell
JF  - Advanced materials
N2  - Organic solar cells are currently experiencing a second golden age thanks to the development of novel non-fullerene acceptors (NFAs). Surprisingly, some of these blends exhibit high efficiencies despite a low energy offset at the heterojunction. Herein, free charge generation in the high-performance blend of the donor polymer PM6 with the NFA Y6 is thoroughly investigated as a function of internal field, temperature and excitation energy. Results show that photocurrent generation is essentially barrierless with near-unity efficiency, regardless of excitation energy. Efficient charge separation is maintained over a wide temperature range, down to 100 K, despite the small driving force for charge generation. Studies on a blend with a low concentration of the NFA, measurements of the energetic disorder, and theoretical modeling suggest that CT state dissociation is assisted by the electrostatic interfacial field which for Y6 is large enough to compensate the Coulomb dissociation barrier.
KW  - driving force
KW  - non-fullerene acceptors
KW  - organic solar cells
KW  - photocurrent generation
Y1  - 2020
U6  - https://doi.org/10.1002/adma.201906763
SN  - 0935-9648
SN  - 1521-4095
VL  - 32
IS  - 9
PB  - Wiley-VCH
CY  - Weinheim
ER  -