TENSILE STRESS INDUCED REDUCTION OF THE NON-RADIATIVE DECAY RATE IN LUMINESCENT CONJUGATED POLYMER FILMS
徐瑞鴻1*, 白小明2, 楊長謀3
1材料與光電科學學系, 國立中山大學, 高雄, Taiwan
2光電系, 元智大學, 中壢市, Taiwan
3材料科學與工程學系, 國立清華大學, 新竹市, Taiwan
* presenting author:徐瑞鴻, email:jhsu@mail.nsysu.edu.tw
Conjugated polymers, with repeating -conjugation structures along the backbones, are endowed with electrical and optical properties that allow various interesting applications. One of the central issues in the conjugated polymer studies is the emission property. We present a work to study the effect of unidirectional tensile stress on the emission properties of the light emitting conjuagted polymers poly [2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene -vinylene] (MEH-PPV) embedded in the polystyrene matrix. Polarization microscopy indicated that the large tensile stresses align MEH-PPV chains parallel to the stress. Fluorescence lifetime imaging (FLIM) measurements indicated that fluorescence lifetime of the stressed polymers increased ~40% to approximately that of the precursor polymer. The photoluminescence spectra was independent of stress suggesting that this increase is not due to changes in radiative decay rates but primarily due to the suppression of non-radiative decay channels. This resulted in a room temperature fluorescence quantum yield of almost 100%. We believe such highly stressed aligned polymer chains have the potential to greatly improve not only optical conversion efficiency but also charge transport in organic devices.


Keywords: conjugated Polymers, MEH-PPV, fluorescence lifetime,