Environmental Engineering Reference
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In this section, the impact of the incorporation of monofunctional PEG-capped
Au NPs into the active layer of polymer blend will be discussed [ 35 ]. The polymer
donor used in the active layer of the OSCs is poly[2,7-(9,9-dioctylfluorene)-alt-2-
((4-(diphenylamino) phenyl)thiophen-2-yl)malononitrile] (PFSDCN) [ 36 ]. The
improvement of V OC , J sc , FF is reported with an appropriate amount of Au NPs
incorporated into the active layer. As a result, after optimization, the improvement
of PCE by *32 % can be achieved [ 35 ]. The theoretical and experimental studies
of effects of LSPR introduced by Au NPs on the optical and electrical properties of
OSCs, particularly the OSC active layer will be discussed in this section.
8.3.1 Overall Device Performances
The absorption spectrum of PFSDCN film is shown in Fig. 8.8 and has two
absorption peaks at around 374 and 518 nm. The chemical structure of PFSDCN is
shown in the inset of Fig. 8.8 . The optical bandgap and oxidation potential of
PFSDCN are 2.05 eV and 0.91 V, respectively. The HOMO is -5.32 eV as
measured by cyclic voltammetry (CV) method and the LUMO is -3.27 eV cal-
culated from HOMO level and optical bandgap. The absorption spectrum of Au
NPs in chloroform/chlorobenzene (1:1 v/v ratio) is shown in Fig. 8.9 with the peak
at *520 nm. The average diameter of Au NPs is *18 nm determined from TEM
measurement (inset of Fig. 8.9 ).
The J-V characteristics are shown in Fig. 8.10 a. The effects of Au NPs con-
centration on performances including V OC ,J sc , FF, and PCE of OSCs with
structure of ITO/PEDOT:PSS (30 nm)/PFSdCN:PCBM (1:4 wt%; 2 mg/ml:8 mg/
ml dissolved in chloroform/chlorobenzene (1:1, v/v ratio)): Au NPs/LiF (1 nm)/
Al(100 nm) are shown in Fig. 8.10 b (i)-(iv), respectively. It should be noted that
the fabrication conditions such as the ratio of PFSDCN to PCBM, spin-coating
Fig. 8.8 The normalized
absorption spectrum and
chemical structure of
PFSDCN [ 35 ]
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