Vacuum electrospray deposition (ESD) equipment was designed to prepare polymer thin films. The polymer solution can be injected directly into vacuum system through multi-stage pumping line, so that the solvent residues and ambient contaminants are highly reduced. To test the performance of ESD system, we fabricated organic photovoltaic cells (OPVCs) by injecting polymer solution directly onto the substrate inside a high vacuum chamber. The OPVC fabricated has the structure of AlP3HT:PCBMPEDOT:PSSITO and was optimized by varying the speed of solution injection and concentration of the solution. The power conversion efficiency (PCE) of the optimized OPVC is 3.14% under AM 1.5G irradiation without any buffer layer at the cathode side. To test the advantages of the vacuum ESD, we exposed the device to atmosphere between the deposition steps of the active layer and cathode. This showed that the PCE of the vacuum processed device is 24 higher than that of the air exposed device and confirms the advantages of the vacuum prepared polymer film for high performance devices.
Bibliographical noteFunding Information:
This work was supported by Samsung Display Company, the KIST Institutional Program (2E22735-12-069) and by a research project of the National Research Foundation of Korea (Grant No. 2012-0002303).
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