Performance Of Solar Cells Based On P3HT:PCBM And Study On The Mechanism

Polymer solar cells (PSCs) have attracted much attention due to their possibilities on low production cost, light weight, mechanical flexibility, green and renewable energy source. In this thesis, based on the basis of the polymer solar cell device, analyze the different functional layers affect the performance of devices, realize different function layer to improve the performance of polymer solar cells. This thesis includes the following several aspects.(1)The performances of P3HT:PCBM solar cells were improved by anode modification using spin-coated Tb(aca)3phen ultrathin film. The modification of Tb(aca)3phen ultrathin film between ITO anode and PEDOT:PSS layer resulted in a maximum PCE of2.99%compared to2.66%for reference device, which was due to the increase in short-circuit current density (Jsc). The PCE improvement could be attributed to short-wavelength energy utilization and optimized morphology of the active layers. Tb(aca)3phen with strong down-conversion luminescence properties is suit for P3HT:PCBM blend active layer, the absorption region of the ternary blend films is extended into near ultraviolet region. Furthermore, the crystallization and surface morphology of P3HT:PCBM films were improved with Tb(aca)3phen ultrathin film. The UV-Visible absorption spectra, atomic force microscope (AFM) and X-ray diffraction (XRD) were investigated. Both anode modification and short-wavelength energy utilization using Tb(aca)3phen in P3HT:PCBM solar cells exhibited a significant increase of12%in PCE.(2)We demonstrate efficiency improvement in PSCs through dual treatments of solution-processed Au nanoparticles (NPs). Au NPs are found to have distinct mechanisms in improving device performance when dispersed on ITO electrode and doped into buffer layer. Au NPs dispersed on ITO electrode mainly contribute localized surface plasmon resonance (LSPR). The PCE was increased from2.64%of the devices without Au NPs to3.34%with dual treatments of Au NPs, mainly from the improved photocurrent density as a result of the excited LSPR induced by the Au NPs.(3)The effect of dimethyl sulfoxide doping concentration on the performance of PSCs based on P3HT:PCBM as the active layer was investigated. The results suggest that the doping of DMSO can improve Jsc and fill factor (FF) of the PSCs. The cell with3%DMSO exhibits an enhanced Jsc (7.88mA/cm2), and FF (55.5%).The optimized PCE arrived to2.54%, which is17%higher than that of the cell without DMSO doping. The increased performance should be attributed to the enhanced charge carrier mobility and widened absorption spectra of P3HT:PCBM through doping DMSO. To investigate the causes of the PCE improvement after addition of DMSO, an enhanced light harvesting and charge carriers transport properties were observed using UV-Visible spectra and J-V characteristics. The absorption peaks of P3HT:PCBM:DMSO thin film show a distinguished red shift and strong absorption compared to P3HT:PCBM thin films in the visible light range. In addition, surface morphology and phase image of pristine P3HT:PCBM and P3HT:PCBM:DMSO blend films were observed through AFM.(4)We also demonstrate efficiency improvement in PSCs through solvent treatment and cathode modification of GQDs. The results suggest that the solvent treatment and cathode modification can improve Jsc of the PSCs. The results exhibit the enhancement of Jsc from8.34mA/cm to9.73mA/cm2.The optimized power conversion efficiency arrived to4.51%, which is23%higher than that of the cell without GQDs.