The Research Of High Outpower Organic Solar Cells Technology

During several years, as the fosil fuel reduces without expectation, many researchers and companies pay a lot of attention and efforts to renewable energy resources. The light from the sun can be converted into electricity by the organic solar cells. This can efficiently solve the problem that the electricity energy is not sufficient. In this thesis we do some research about high outpower organic solar cells technology in three points.The 4,4’-N,N’-dicarbazole-biphenyl n-doped Mo O3(MoO3:CBP, 15:1 in mass) has been fabricated and applied to inverted organic light emitting diode(IOLED) and polymer solar cell(IPSC). The composite anode of MoO3:CBP(15:1) 7nm/MoO3 3nm/ Al presented markedly increased hole current for the IOLED than the conventional composite anode of MoO3 10nm/ Al. It showed slightly increased power conversion efficiency for the IPSC relative to the conventional one, attributed to that the electron accumulation established at the MoO3 side of the homointerface limited the hole extraction under the short-circuit condition, counteracting the conduction advantage of the MoO3:CBP(15:1) over the neat MoO3. We provide an easy, effective concept of developing high-conductivity hole injection materials for organic electronic devices.The poly(3-hexylthiophene)(P3HT), [6,6]-phenyl C61-butyric acid methyl ester(PCBM), and polymethylmethacrylate(PMMA) have been chosen to constitute binary and ternary blend thin films. In the case of the binary blend thin films of P3HT:PCBM used as the photoactive layers, the LiF/Al cathode offered nearly the same power conversion efficiency(PCE) as the bathocuproine(BCP) 2 nm/Al and BCP 10 nm/Al cathodes. While the ternary blend thin films of P3HT:PCBM:PMMA were applied as the photoactive layers, the BCP 2 nm/Al cathode showed an increase of roughly 42% in the PCE relative to the LiF/Al and BCP 10 nm/Al cathodes. The vertical phase separation of P3 HT and PCBM was found suppressed in the ternary blend films than in the binary ones, due to the confinement of PMMA. The P3HT:PCBM:PMMA with the BCP 2 nm/Al cathode showed an increase of 20% in the PCE than the P3HT:PCBM with the LiF/Al cathode. We provide some insights on the correlation between the morphology control and device structure, useful for the development of polymeric solar cells towards the commercialization.In order to increase the open-circuit voltage and lifetime of the polymer solar cell, we provide a new concept of using bathocuproine(BCP) as a buffer layer in polymer solar cell. For P3HT:PCBM thin film used as the photoactive layer, since P3 HT has a lower surface energy than PCBM, P3 HT tends to accumulate at the air surface in order to reduce the overall energy. The solvent evaporation process during spin-coating allows the morphology to reach a thermodynamically favorable state via vertical phase separation. As a result, there exists a apparent concentration gradient varying from the PCBM-rich part near the poly(3,4-ethylenedioxythiophene)/poly(styene-sulfonate)(PEDOT:PSS) side to P3HT-rich adjacent to the free(air) surface. There exists a photovoltaic effect between P3 HT and BCP, increasing the open-circuit voltage of the polymer solar cell. So the open-circuit voltage of the polymer solar cell, whose structure is ITO/PEDOT:PSS/P3HT:PCBM/BCP/Al, is much larger than that, whose structure is ITO/PEDOT:PSS/P3HT/BCP/Al. What’s more, BCP can block the diffusion of Al atom to the photo-active layer, decreasing the quenching of the excitons. For P3HT:PCBM used as the photo-active layer, the LiF/Al cathode offered nearly the same power conversion efficiency as bathocuproine(BCP)/Al cathode. So bathocuproine(BCP) as a buffer layer can increase the lifetime of the polymer solar cell instead of LiF. Bathocuproine(BCP) as a buffer layer is useful for the research of high outpower organic solar cells technology.