18 Interfacial Materials for Organic Solar Cells
413
18.3 Conclusions and Outlook
In this chapter we have explored some cathode and anode interfacial materials and
their role in solution-processed organic solar cells. Together with the development of
novel active layer materials (polymers or oligomers), the interfacial materials design
have found equal importance toward their role in device performance improvement.
These interlayer materials have gained tremendous interest in recent years and been
successfully employed in high performance conventional and inverted devices. A
structure-property device performance relationships have been established which
is beneficial for the development of new interlayer materials. Furthermore, with
an effort towards molecular design, from neutral to charged materials, the optical
properties, energy levels, charge carrier mobilities, conductivity, work function as
well as surface morphology and surface energy can be tuned, and therefore affecting the OSC performance. When these materials are combined with suitable donor:
acceptor photoactive layers and device processing conditions high performance single junction solar cells reaching PCEs >10% have been achieved. Recently, record
PCE exceeding 17% was reported for an inverted tandem cell using ZnO/PFN-Br as
CIL, PEDOT:PSS/ZnO as interconnecting layer and MoO 3 /Ag as AIL showing the
importance of molecular design of different active layers, interlayers and device engineering (Meng et al. 2018). Apart from device efficiency, the device stability is also
an important issue which was almost solved by the use of metal oxides as interlayer
in inverted devices. Simultaneously, together with the performance the use of organic
and polymeric interlayers have also shown tremendous improvement in device stability. Sometime very thin interlayer is sufficient to get high efficiency. However,
for practical applicability of the technology it is also important to develop thickness
insensitive interlayers which are very rare at this moment. Now it is also important to
exploit the potential of various interlayer materials in different device configuration
which could open up new opportunities towards performance improvement and PCE
of >20% is not far to reach.
Acknowledgements The authors would like to acknowledge the Sambalpur University for providing research infrastructure and Department of Science and Technology (DST), New Delhi
(DST/TMD/SERI/D05) for financial support.
References
Aryal UK, Chakravarthi N, Park H-Y, Bae H, Jin S-H, Gal Y-S (2018) Highly efficient polyacetylene–based polyelectrolytes as cathode interfacial layers for organic solar cell applications.
Org Electron 53:265–272
Baek S-W, Park G, Noh J, Cho C, Lee C-H, Seo M-K, Song H, Lee J-Y (2014) Au@Ag core-shell
nanocubes for efficient plasmonic light scattering effect in low bandgap organic solar cells. ACS
Nano 8(4):3302–3312
Bao X, Sun L, Shen W, Yang C, Chen W, Yang R (2014) Facile preparation of TiO X film as an
interface material for efficient inverted polymer solar cells. J Mater Chem A 2(6):1732–1737
413
18.3 Conclusions and Outlook
In this chapter we have explored some cathode and anode interfacial materials and
their role in solution-processed organic solar cells. Together with the development of
novel active layer materials (polymers or oligomers), the interfacial materials design
have found equal importance toward their role in device performance improvement.
These interlayer materials have gained tremendous interest in recent years and been
successfully employed in high performance conventional and inverted devices. A
structure-property device performance relationships have been established which
is beneficial for the development of new interlayer materials. Furthermore, with
an effort towards molecular design, from neutral to charged materials, the optical
properties, energy levels, charge carrier mobilities, conductivity, work function as
well as surface morphology and surface energy can be tuned, and therefore affecting the OSC performance. When these materials are combined with suitable donor:
acceptor photoactive layers and device processing conditions high performance single junction solar cells reaching PCEs >10% have been achieved. Recently, record
PCE exceeding 17% was reported for an inverted tandem cell using ZnO/PFN-Br as
CIL, PEDOT:PSS/ZnO as interconnecting layer and MoO 3 /Ag as AIL showing the
importance of molecular design of different active layers, interlayers and device engineering (Meng et al. 2018). Apart from device efficiency, the device stability is also
an important issue which was almost solved by the use of metal oxides as interlayer
in inverted devices. Simultaneously, together with the performance the use of organic
and polymeric interlayers have also shown tremendous improvement in device stability. Sometime very thin interlayer is sufficient to get high efficiency. However,
for practical applicability of the technology it is also important to develop thickness
insensitive interlayers which are very rare at this moment. Now it is also important to
exploit the potential of various interlayer materials in different device configuration
which could open up new opportunities towards performance improvement and PCE
of >20% is not far to reach.
Acknowledgements The authors would like to acknowledge the Sambalpur University for providing research infrastructure and Department of Science and Technology (DST), New Delhi
(DST/TMD/SERI/D05) for financial support.
References
Aryal UK, Chakravarthi N, Park H-Y, Bae H, Jin S-H, Gal Y-S (2018) Highly efficient polyacetylene–based polyelectrolytes as cathode interfacial layers for organic solar cell applications.
Org Electron 53:265–272
Baek S-W, Park G, Noh J, Cho C, Lee C-H, Seo M-K, Song H, Lee J-Y (2014) Au@Ag core-shell
nanocubes for efficient plasmonic light scattering effect in low bandgap organic solar cells. ACS
Nano 8(4):3302–3312
Bao X, Sun L, Shen W, Yang C, Chen W, Yang R (2014) Facile preparation of TiO X film as an
interface material for efficient inverted polymer solar cells. J Mater Chem A 2(6):1732–1737