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Low-temperature, solution-processed, layered V2O5 hydrate as the hole-transport layer for stable organic solar cellsElectronic supplementary information (ESI) available. See DOI: 10.1039/c3ee42204f
Layered V 2 O 5 hydrate has been applied as the hole transport layer (HTL) in organic solar cells (OSCs). V 2 O 5 is obtained from a sodium metavanadate solution in water under ambient conditions, resulting in a final thin film of formula V 2 O 5 ·0.5H 2 O. The 0.5 water molecules are not removed fr...
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| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Online Access: | Get full text |
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| Summary: | Layered V
2
O
5
hydrate has been applied as the hole transport layer (HTL) in organic solar cells (OSCs). V
2
O
5
is obtained from a sodium metavanadate solution in water under ambient conditions, resulting in a final thin film of formula V
2
O
5
·0.5H
2
O. The 0.5 water molecules are not removed from the V
2
O
5
layered structure unless the sample is heated above 250 °C, which makes the thin film highly stable under real working conditions. The HTL was used in OSCs in the normal and the inverted configurations, applying metallic Ag as the back-metal electrode in both cases. Fabrication of both OSC configurations completely by solution-processing printing methods in air is possible, since the Al electrode needed for the normal-configuration OSC is not required. The work function (WF) and band gap energy (BG) of the V
2
O
5
thin films were assessed by XPS, UPS and optical analyses. Different WF values were observed for V
2
O
5
prepared from a fresh V
2
O
5
-isopropanol (IPA) solution (5.15 eV) and that prepared from a 24 h-old solution (5.5 eV). This difference is due to the gradual reduction of vanadium (from V
5+
to V
4+
) in IPA. The OSCs made with the V
2
O
5
thin film obtained from the 24 h-old V
2
O
5
-IPA solution required photo-activation, whereas those made with the freshly obtained V
2
O
5
did not. Outdoor stability analyses of sealed OSCs containing a V
2
O
5
HTL in either configuration revealed high stability for both devices: the photovoltaic response at
T
80
was retained for more than 1000 h.
Stable organic solar cells have been fabricated applying a water-based low-temperature solution processable V
2
O
5
hydrate as the hole transport layer. |
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| ISSN: | 1754-5692 1754-5706 |
| DOI: | 10.1039/c3ee42204f |