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systems. Different charge separation efficiency and lifetime of CS
2. Experimental and computational methods
states were achieved by changing the donor and second acceptor in
D-TRC-A2 systems. MTPA-TRC exhibits similarly low photoelectric
conversion efficiency (ƞ ¼ 0.03%) in the single-layer OSCs with
common organic semiconductors such as phthalocyane, poly(-
phenylenevinylene) and triarylamine derivatives [9,21e23] of
which the efficiency has been improved to greater than 6% and can
even exceed 10% by the combined application of other semi-
conductors and the proper design of solar cell structures [9,24e27].
Importantly, the single-layer OSC constructed using MTPA-TRC-
AEAQ (ƞ ¼ 0.89%) with long-lived CS states (650 ns) was found to
be significantly more efficient than that using MTPA-TRC. It in-
dicates that single-layer OSCs had been proven to be the highly
effective cell structure reflecting the effect of CS states with
different lifetimes of organic materials, and the far better photo-
voltaic characteristics of D-TRC-A2 than D-TRC suggests potential
applications in OSCs, if better structural designing of OSCs.
In this paper, we investigate the effects of intramolecular elec-
tron transfer on the light-stability of D-TRC-A2 systems, and report
the results and analyse the effects of second acceptors on the de-
gree of dissociation, which are relative to the electron transport
process. D-A system MTPA-TRC and D-TRC-A2 systems MTPA-TRC-
AEAQ and MTPA-TRC-PBI will be taken as the examples (Chart 1),
where experimental and computational results indicated that some
dissociations of the chloride anions exist in MTPA-TRC due to the
effective PET process from the excited MTPA to the TRC module.
However, the dissociation has been found to be less frequent in
MTPA-TRC-AEAQ and MTPA-TRC-PBI because of the sequential
electron transfers from excited MTPA to the TRC followed by the
AEAQ (or PBI) module, making MTPA-TRC-AEAQ and MTPA-TRC-PBI
more stable under irradiation.
2.1. Materials
Structures of the key compounds being 0synthesized and studied
in this work are provided in Chart 1. 4,4 -dimethyl-400-styryl-tri-
phenylamine (MTPA) [18], 4,40-dimethyl 400-(4-(4,6-dichloro-1,3,5-
triazin-2-ylamino)styryl)triphenylamine (MTPA-TRC) [18], 1-(2-
aminoethylamino)anthraquinone (AEAQ) [18], 1-((4,6-dichloro-
1,3,5-triazin-2-ylamino)ethylamino)-9,10-anthraquinone (AEAQt)
[18],
4,40-dimethyl-400-(4-(6-dichloro-1,3,5-triazin-2-ylamino-4-
ethylamino)styryl)triphenylamine (MTPA-TRC-EA) [18], 4,40-dime-
thyl-400-(4-(6-dichloro-1,3,5-triazin-2-ylamino-4-phenylamino)st-
yryl)triphenylamine (MTPA-TRC-BA) [20], D-A1-A2 systems 4,40-
dimethyl-400-(4-(4-chloro-6-(2-(9,10-dioxoanthracen-1-ylamino)
ethylamino)-1,3,5-triazin-2-ylamino)styryl)triphenylamine
(MTPA-TRC-AEAQ) [18], and 4,40-dimethyl-400-(4-(4-Chloro-6-(N-
(1-hexylheptyl)-N0-(4-amino)phenyl-1,7-di(4-tert-butylphenoxyl)
-perylene-3,4,9,10-tetracarboxylbisimide)-1,3,5-triazin-2-ylamino)
styryl)triphenylamine (MTPA-TRC-PBI) [20] were prepared ac-
cording to the literatures. cyanuric chloride (TRI) and melamine
(Mela) were purchased. The synthetic pathways of 2,4-dichloro-6-
anilino-1,3,5-triazine (TRC-Ph), 2-chloro-4,6-dianilino-1,3,5-triazi-
ne (TRC-diPh), 2,4,6-trianilino-1,3,5-triazine (TRC-triPh) and 4,40-
dimethyl-400-(4-(6-dichloro-1,3,5-triazin-2-ylamino-4-cyano)sty-
ryl)triphenylamine (MTPA-TRC-CN) were illustrated in Scheme 1.
All reagents and solvents were in reagent grade and further purified
by the standard methods if necessary. All synthetic procedures
were carried out under an atmosphere of dry nitrogen or dry argon
unless otherwise indicated.
Chart 1. The structure of key compounds.