The Fabrication and Investigation of Organic Tandem Solar Cells

Abstract

Recently, the shortage of gasoline is getting serious. As a result, people pay much more attention to solar cells. Unfortunately, high cost is always a main problem for inorganic silicon solar cells to apply commercially. With characteristics of simple and cost-effective fabrication process, moreover, flexible materials being the substrate, organic solar cells play an more and more important role in the future. We try to fabricate three kinds of tandem cells. The first cell is a bulk heterojunction consisting blending of P3HT and PCBM combined with blending of CuPc and C60 by gold as an interlayer. The efficiency of spectrum absorption will be enhanced by means of matching two active layers with complementary spectrum range. The blending of P3HT and PCBM was spin-coated on ITO-coated glass and small molecules was coated by evaporation. The second cell is combination of two conjugated polymers with the same interlayer and it is all-solution process. We adjust concentration ratio between P3HT and PCBM of two unit cells to make them absorb different spectrum range. The third one is formed by one normal-cell sticking to one inverted-cell. The main work we studied is the method how to fabricate tandem cells and how to accurately define areas overlapped by every layer. Finally, we also studied how to reasonably and correctly measure tandem cells and the effect of two unit cells.