| Summary: | 碩士 === 國立交通大學 === 光電系統研究所 === 104 === Solid-state near-infrared (NIR) light-emitting electrochemical cells (LECs) possess great potential in applications of NIR light sources due to their simple device structure, low operating voltage and compatibility with large area and flexible substrates. However, common host-guest NIR LECs suffer from the problem of significantly enhanced residual host emission when increasing bias voltage to achieve higher NIR light output. Higher NIR light output can only be obtained at the expense of spectral purity in host-guest NIR LECs. To enhancing NIR light output of LECs without sacrificing spectral purity significantly, a novel approach to generate NIR EL from host-only red-emitting LECs by adjusting device thickness to modify microcavity effect is proposed. NIR EL from host-only red-emitting LECs can be realized by adjusting device thickness to shift peak wavelength for constructive interference at NIR spectral region. NIR EL resulted from microcavity effect is relatively insensitive to bias voltage. Therefore, without losing spectral purity significantly, 20X enhancement in NIR output has been obtained in comparison to previously reported value from host-guest NIR LECs. These results reveal that tailoring EL spectra of host-only red-emitting LECs via modifying microcavity effect would be a promising way to generate higher NIR light output without suffering from residual host emission problem of host-guest NIR LECs.
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