Study On The Correlation Between P3HT:PCBM Polymer Solar Cell Morphology And Properties Of The Active Layer

The morphology of active layer of polymer solar cells strongly depends on preparation conditions. Spin coating-method has been used to prepare the P3HT:PCBM blend films. The effect of the mass ratios of the blend composition, dual optimization of solvent annealing and thermal annealing on the performance and morphology of P3HT:PCBM blend active layer has been studied by adjusting the spin-coating time, annealing temperature and the mass ratios of P3HT:PCBM blend. The morphology and optical absorption of the P3HT:PCBM blend films have been characterized by X-ray diffraction(XRD) analyses, atomic force microscopy(AFM) and UV-Vis spectroscopy.Firstly, the P3HT:PCBM blend films on the ITO conductive glass substrate have been obtained by spin coating-method, in which P3 HT and PCBM are used as the precursor, chlorobenzene as solvent. The P3HT:PCBM blend films with different mass ratio have been studied under spin coating rate of 1000 r·min-1, spin coating time of 30 s, solvent annealing time of 30 min and thermal annealing time of 20 min at 150℃. The results showed that the particles distributed on the surface of the films were homogeneous and their roughness was 11.7 nm when the mass ratio of 1:1. The X- ray diffraction studies show that minimum half peak width of 0.41 degrees was found at mass ratio of the blend is 1:1, which improved the carrier mobility; UV-Vis absorption spectra show that the absorption peak of P3 HT caused by gathering is strongest;Secondly, the blend film with mass ratio of 1:0.8 has been studied under adjusting the spin-coating time between 20~90 s(solvent annealing time) and thermal annealing temperature between 120~180℃. The results showed that the blend film with spin coating time of 30 s exhibit better performance and the surface roughness is 8.52 nm. We obtained surface roughness of 10.3 nm under annealing temperature of 150 ℃.Thus, the best conditions of preparation of P3HT: PCBM blend film are spin coating speed of 1000 r·min-1, spin coating time of 30 s and thermal annealing temperature of 150℃.which provides a basis for the improvement of polymer solar cell photoelectric conversion efficiency.