Photovoltaic devices based on polymer materials for renewable electrical power and sustainable energy have been the target of research worldwide and substantial progress in numerous aspects. There are many advantages of polymer solar cells such as low cost, light weight, large area, mechanical flexibility and easy to process ability.
The aforementioned factors influence the efficiency of photovoltaic cells, the absorption spectrum of the active layer, the morphology, donor and acceptor’s HOMO and LUMO level, film morphologies, charge carrier mobility and the work functions of electrodes. Also the performance of polymer solar cells has been improved by using new materials and new structure in devices.
Improvement of the photovoltaic efficiency via exposure of organic poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) devices to Li:Al cathode and solvent swelling treatment are reported here. The organic solar cells with Li:Al alloy cathode are effect to the increased Jsc for may be attributed to the improved contact at the cathode interface and therefore the electron transport is improved. It measured by UPS, XPS, and dynamic-SIMS. And also we have demonstrated that solvent swelling treatment of P3HT:PCBM film leads to a marked increase in the ordering of P3HT as observed by AES, UV-vis absorption spectra, and AFM.