Deposition properties of small molecular organic thin films by multi-jet mode electrospray deposition

Development of solution based small-molecular organic thin film deposition technique is important for further prevalence and expansion of the combinatorial variety of materials for organic devices. The electrospray deposition (ESD) is a candidate of the wet deposition technique of organic materials. In this study, we investigated the deposition characteristics of mixed small molecular organic material of CBP:PBD:TPD:Ir(mppy)
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using chlorobenzene solution with three typical spray modes of the Taylor-cone, the convergent-jet and the multi-jet modes. We measured the size distribution of deposited solute marks by SEM observation and compared the surface morphology of thick films for each spray mode. It was confirmed that MJ-mode could deposit solutes with smallest diameter less than 1 µmm with smallest size deviation and could deposit smoothest film with surface roughness RMS of 3.5 nm. We also investigated the effect of additive solvent of dimethyl-sulfoxide and concentration of solute on the deposition characteristics of MJ-mode ESD.