PTB7:PC71BM. The current density–voltage (J–V) characteristics were
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model 91192), under light intensity of 100 mW cm−2
.
Mobility Measurements using the Time-of-Flight (TOF) Technique:
Device configuration (ITO/Alq3/Phen-NaDPO/Al). Alq3 (20 nm) and
Phen-NaDPO (1.5 µm) were deposited by thermal evaporation in
vacuum (< 6 × 10-4 Pa) at a rate of 0.2 and 3 Å s−1, respectively. The
Al electrode (15 nm) were thermally deposited through a mask. The
effective device area was about 0.04 cm2. A Nd:YAG laser (λ = 355 nm,
pulse width: 5 ns) was used as the light source and Alq3 as the charge-
generation layer (CGL). The applied voltage was controlled by a Keithley
2400 source meter. The electrons moved toward the Al contact with a
negative voltage. The photocurrent was characterized across the load
resistor using a digital storage oscilloscope (DPO7104, bandwidth:
1 GHz). The electron mobility was deduced from
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Acknowledgments
X.H.Z. is grateful for the financial support of SCUT, NSFC, and MOST of
China (Grant Nos. 2014CB643500, 2014ZG0009, 51173051, U1301243,
and 91333206). W.C. acknowledges the financial support from Singapore
MOE Grants R143–000–505–112, R143–000–530–112, R143–000–542–
112 and R143–000–559–112. W.C.H.C. would like to acknowledge the
financial support of the Research Grants Council (RGC) of Hong Kong
Special Administrative Region for the General Research Fund (grants:
HKU711813 and HKU711612E), the RGC-NSFC grant (N-HKU709/12)
and the ERG-SRFDP grant (M-HKU703/12). The authors are thankful to
Prof. Wei-Hong Zhu at East China University of Science and Technology
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Adv. Funct. Mater. 2014,
DOI: 10.1002/adfm.201401685