Research On The P3HT: PCBM Polymer Solar Cells

Compared with the conventional solar cells, polymer solar cells have uniqueadvantages, such as: low-cost, simple reparation process, lightweight and convenient.This kind of solar cells is expected to become the alternative energy in the futurebecause of these advantages. Many research groups have been devoted to thedevelopment of polymer solar cells.In this paper, Effects of the deposition of Al electrode, annealing processes andthe improvement of structure on the cells which based on P3HT as donor and PCBMas acceptor were studied. Effects of different solvents on the active layer were also=studied primitively.Firstly,deposition of Al electrode was investigated in detail. It was found that thecrystallinity and the grain size of Al film increased with the increasing of rate andthickness of deposition. The performance of the cells also improved with appropriateincreasing of deposition rate. The Jsc of the cells increased with the increasing ofthickness of Al electrode, but the Voc and FF decreased at the same time and ultimatelythe performance of the cells declined.Then, the annealing processes and improvement of structure of the cells werestudied. It was found that performance of the polymer solar cells treated with postannealingprocess were improved more effectively compared with those treated withpre-annealing process, the efficiency of the solar cells arrived at 1.93% (Voc = 0.60V,Jsc=5.89mA/cm2, FF=54.7%) through post-annealing treatment. Inserting a PCBMlayer of appropriate thickness between the Al electrode and the active layer couldmake the cell structure more ideal, and performance of solar cells improved furthermore. When the thickness of PCBM was 3nm, the Jsc of the solar cell reached to6.43mA/cm2, Efficiency was also increased to 2.09%. However, when thickness of the PCBM was further increased, the performance of the solar cell declined.Finally, the effects of different solvents include chlorobenzene and 1,2-dichlorobenzene on the active layer were investigated primitively. It was found thatthe effects of the solvent on the thickness and microstructure of the active layer weregreat. Thinner active layer and more ideal phase separation was obtained when 1,2-dichlorobenzene used as solvent under the same condition. P3HT and PCBM in theactive layer could not be separated effectively when chlorobenzene used as solvent.However, it can be significantly improved after annealing treatment.