Ryo Terada

Deposition characteristics of small-molecule CBP:PBD:TPD:Ir(mppy)3 organic thin films using a modified electrospray deposition method

The development of a solution-based technique for the deposition of small-molecule organic thin films is desirable for the advancement of organic devices. In this study, we investigated the deposition characteristics of an organic thin film deposited by modified electrospray deposition with three typical spraying modes: Taylor cone, convergent jet, and multijet. The results indicate that the multijet mode can generate the smallest droplets with the narrowest size distribution. Using the multijet mode, we deposited a pinhole-free, smooth CBP:PBD:TPD:Ir(mppy)3 small-molecule organic film with a root-mean-square surface roughness of 2.5 nm.

Fabrication of Alq3/NPB small-molecule laminated structures with suppressed interface mixing by multi-jet mode electrospray deposition

Realization of wet fabrication process for small-molecule laminated structures are attractive to spread the application field of high performance organic devices due to large area capability and cost effective mass production. In this study, we present Alq3/NPB small-molecule laminated structures with suppressed interface mixing by electrospray deposition (ESD). It was shown that ESD can deposit Alq3 solution with small diameter of less than 1 μm with small deviation by use of multi-jet (MJ) mode. The surface roughness RMS of Alq3 layer deposited by the MJ-mode ESD was reduced to be 3.3 nm. It was revealed by a surface morphology observation at initial deposition stage and analysis of photoluminescence spectra of laminated structure, the optimization of deposition condition could suppress the surface erosion and interface mixing between Alq3 and NPB layers. It was demonstrated that the MJ-mode ESD is a strong candidate of wet fabrication process of small-molecule laminated structures.

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)3 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.