10.1021/acsami.6b15631.s001
Chunyu Liu
Chunyu
Liu
Dezhong Zhang
Dezhong
Zhang
Zhiqi Li
Zhiqi
Li
Xinyuan Zhang
Xinyuan
Zhang
Wenbin Guo
Wenbin
Guo
Liu Zhang
Liu
Zhang
Liang Shen
Liang
Shen
Shengping Ruan
Shengping
Ruan
Yongbing Long
Yongbing
Long
Boosted
Electron Transport and Enlarged
Built-In Potential by Eliminating
the Interface Barrier in Organic Solar Cells
American Chemical Society
2017
WF
champion power conversion efficiency
electron injection devices
TiO 2 ETL
TiO 2 film
PCE
Boosted Electron Transport
PL
barrier
PC 71 BM
electron transfer
acceptor
charge carrier recombination
TiO 2 electron transport layer
TRTPL
V oc
PFN interlayer
TiO 2
J sc
photoluminescence
Organic Solar Cells
interface modification strategy
2017-02-24 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Boosted_Electron_Transport_and_Enlarged_Built-In_Potential_by_Eliminating_the_Interface_Barrier_in_Organic_Solar_Cells/4718920
A smart interface
modification strategy was employed to simultaneously
improve short-circuit current density (<i>J</i><sub>sc</sub>) and open-circuit voltage (<i>V</i><sub>oc</sub>) by incorporating
a poly[(9,9-bis(3′-(<i>N</i>,<i>N</i>-dimethylamion)propyl)-2,7-fluorene)-<i>alt</i>-2,7-(9,9-dioctyl)-fluorene] (PFN) interlayer between
a TiO<sub>2</sub> film and an active layer, arising from the fact
that PFN effectively eliminated the interface barrier between TiO<sub>2</sub> and the fullerene acceptor. The work function (WF) of TiO<sub>2</sub> was apparently reduced, which facilitated effective electron
transfer from the active layer to the TiO<sub>2</sub> electron transport
layer (ETL) and suppressed charge carrier recombination between contact
interfaces. Electron injection devices with and without a PFN interlayer
were fabricated to prove the eliminated electron barrier, meanwhile
photoluminescence (PL) and time-resolved transient photoluminescence
(TRTPL) were measured to probe much easier electron transfer from
[6,6]-phenyl C71-butyric acid methyl ester (PC<sub>71</sub>BM) acceptor
to TiO<sub>2</sub> ETL, contributing to enhanced <i>J</i><sub>sc</sub>. The shift in vacuum level altered the WF of PC<sub>71</sub>BM, which enlarged the internal electrical field at the donor/acceptor
interface and built-in potential (<i>V</i><sub>bi</sub>)
across the device. Dark current characteristics and Mott–Schottky
measurements indicated the enhancement of <i>V</i><sub>bi</sub>, benefiting to increased <i>V</i><sub>oc</sub>. Consequently,
the champion power conversion efficiency for a device with a PFN interlayer
of 0.50 mg/mL reached to 7.14%, which is much higher than the PCE
of 5.76% for the control device.