S-Space College of Engineering/Engineering Practice School (공과대학/대학원) Dept. of Material Science and Engineering (재료공학부) Journal Papers (저널논문_재료공학부)
Thickness dependence of PL efficiency of organic thin films
- Jeong, Won-Ik; Kim, Sei Yong; Kim, Jang-Joo; Kang, Jae Wook
- Issue Date
- Chem. Phys. 355 (2009) 25
- PL efficiency of thin films; Surface quenching; Waveguide; Weak microcavity; Thickness dependence
- Thickness dependence of photoluminescence (PL) efficiency and spectral shape of phosphorescent organic thin films is investigated and theoretically analyzed. The PL efficiency increases with increasing thickness to reach the maximum 92% at around 50 nm. It reduces to 77% at the thickness of 130–140 nm and oscillates between the values upon further increment of thickness. The quenching of excitons at the surface of organic layer significantly reduces the PL efficiency when the film is very thin. If the film is thicker than the critical thickness for the waveguiding of emitted light, the waveguided power is absorbed during the propagation through the organic layer so that apparent PL efficiency is reduced by the amount. Microcavity effect formed by quartz/organic layer/air also affects the PL efficiency. The appropriate thickness to obtain the PL efficiency close to the intrinsic value of a film is just the critical thickness for waveguiding through the film.
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