The Study Of Small Organic Molecular Photovoltaic Devices With Mixed Donor

Recently, photovoltaic cells(OPV) has become one of common means to exploit solar energy. Among various kinds of cells, organic photovoltaic cells have caught world’s attention due to their distinctive advantages: low cost, abundant kinds of materials and simple fabrication process. However, their significantly lower efficiency compared with silicon-based solar cells remains a problem yet to be conquered.For the first part, We used Bphen as the cathode modified layer and studied the role in the organic thin film solar cells. The basic OPV structure was ITO/PEDOT:PSS /P3HT:PCBM/Bphen/Ag, With Bphen buffer layer thickness increasing, the short circuit current density(Jsc) first increases then decreases. When the thickness of Bphen layer increased to 10 nm, short circuit current density reaches the maximum, 12.64 mA/cm2; open circuit voltage(Voc) increased from 0.06 V to 0.56 V, which improved an order of magnitude. Bphen cathode modified layer effectively improve the device parameters such as open circuit voltage and short circuit current, thus improve the photoelectric conversion efficiency of flexible organic thin-film photovoltaic device.Secondly, we based on the structure which Bphen as cathode buffer layer, studied the double donor devices. We first used a combination of Pentacene and Rubrene, making the devices ITO/PEDOT:PSS/Pentacene/Rubrene/C60/Bphen/Ag. The results showed that when the Pentacene was 5 nm and Rubrene was 15 nm, the efficiency of the battery got the largest, the effciency has been increased from 0.821% to 1.132%, the open circuit voltage increased from 0.35 V to 0.67 V. Moreover, we adopted the combination of Rubrene and SubPc. In this experiment, when Rubrene was 5 nm and SubPc was 15 nm, the device reached the highest conversion, 1.775%. The final group was the combination of Irppy3 and Rubrene. When Irppy3 was 5 nm and Rubrene was 15 nm, it reached the highest efficiency, 1.176%. This experiment verified that the double donor layer structure can greatly improve the efficiency of battery components.Finally, we based on the structure of double donor layer, mixed the two layers each other. First of all, what we used was the combination of Rubrene and SubPc, thickness was the same with the third chapter, 20 nm. We controled the mix proportion of Rubrene and SubPc for 1:0, 3:1, 1:1, 1:3, and 1:0, which corresponded to the third chapter of Rubrene / SubPc(20/0, 15/5, 10/10, 5/15, 0/20). The hybrid structure of the device’s maximum efficiency was 1.374 times larger than the thin layer device of maximum efficiency. Secondly we used Pentacene and Rubrene as experiment material, to the same layer thickness of 20 nm. We controled the mix proportion of Pentacene and Rubrene was 1:0, 3:1, 1:1, 1:3, and 1:0, respectively, this also corresponds to the third chapter of Pentacene/Rubrene(20/0, 15/5, 10/10, 5/15, 0/20). Combination of the experimental results of chapter 3 and chapter 4, for Pentacene/Rubrene, the third chapter to achieve the highest conversion efficiency of 1.312%, and 1.580% in the fourth chapter, increased by 20.4%; for Rubrene/SubPc, the third chapter of the highest conversion efficiency is 1.775%, 2.440% in the fourth chapter, increased by 37.5%. So, the mixed layer can improve the device efficiency further.