Environmental Engineering Reference
In-Depth Information
incorporated in the active layer can utilize LSPR to improve active layer
absorption. On the other hand, electrical properties are found to play significant
roles in improving PCE. Our studies highlight the important point that both
electrical and optical characteristics have to be investigated in OSCs, and our
findings are highly useful in the design of NP-incorporated solar cells.
In
Sect. 8.4
, Au NPs incorporated into both the hole collection layer and the
active layer have been discussed. A large increase in PCE (*22 %) has been
reported [
56
] which is attributed to the stacked improvements of NPs incorporating
in the hole collection layer and the active layer. Coupling is not observed between
NPs in the different layers, but this study shows that NPs can be incorporated in all
layers to achieve large improvements in efficiency.
Appendix A
The electrical properties of OSCs with Au NPs in the active layer of PFSDCN:
PCBM [
35
] have been theoretically studied by solving the organic semiconductor
equations involving Poisson, drift-diffusion, and continuity equations [
42
,
46
,
59
].
The field-dependent mobility uses the Frenkel-Poole form l = l
0
exp(F/F
0
). The
Braun-Onsager model is employed for the exciton dissociation. The boundary
conditions for ohmic or schottky contacts are also taken into account.
Due to the very thin active layer (*65 nm), it can be assumed the generation
rate of bound electron-hole pairs (G
max
) is uniform. G
max
can be obtained from the
measured absorption spectra. The electron and hole mobilities can be obtained by
fitting the J-V curves of the measured electron- and hole-only devices following
the SCLC model. The HOMO is -5.32 eV as measured by cyclic voltammetry
(CV) method and the LUMO is -3.27 eV calculated from HOMO level and
optical bandgap. The exciton decay rate (k
F
) of exciton and charge separation
distance (a) can be fitted to make our theoretical J-V curves best fit to the
experimental J-V curves
References
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