Application of Graphene as Electrodes and Hole Transport Layer for Polymer Solar Cells
Date Issued
2012
Date
2012
Author(s)
Yang, Ya-Ting
Abstract
In this thesis, the graphene was applied as transparent electrodes and the hole transport layer in organic solar cells (OPVs). The first part was the graphene transparent electrode as the top anode of bifacial semitransparent inverted OPVs. Solvent vapor annealing process could enhance power conversion efficiency of both sides. In the second part, by chemical doping of graphene, the surface charge transfer between the dopant and the graphene changed the graphene work function and the majority carrier. The N-dopants PEI, TiOx, BCP, TPBi and P-dopant the F4-TCNQ were used. Furthermore, N-doped and P-doped graphene were applied as cathode and anode respectively. From the experimental results, the N-doped graphene as a cathode of OPVs based on P3HT:PCBM was still a challenge, and PEI-doped graphene was a more effective cathode. The final part was graphene hole transport layer of inverted OPVs. There was high compatibility of dry transfer process of graphene and solution process of OPVs. The results shown that graphene as a hole transport layer of inverted OPVs, not only worked under the general high work function electrode as anode but also worked under low work function aluminum electrode as anode. The aluminum Fermi level was pinned near the graphene Fermi level, which overcame the mismatch of the aluminum electrode work function and light absorption layer material P3HT HOMO energy level that caused low power generation efficiency. And it exhibited a high power conversion efficiency of 2.9%. Therefore, the lower-cost aluminum electrode was available to replace the original high cost of silver electrode.
Subjects
graphene
hole transport layer
electrode
dope
Type
thesis
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