有機金屬螯合物之時間解析光激螢光研究

Abstract

Since the discovery of luminescence from organic materials, there has been a considerable amount of efforts devoted to developing organic light emitting devices for use in display applications. Recently, organic light emitting materials also emerge as the candidate for highly efficient active media for lasers. And significant enhancement of spontaneous emission by coupling with surface plasmonic energy transfer has been demonstrated for organic materials. In this work, we studied the surface plasmon-induced enhancement of spontaneous emission and estimated the Purcell factors from three organic chelates dyes doped by 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM), Znq:DCM (2.5%), BAlq:DCM (2.5%), and Alq3:DCM (2.5%). Besides the time-integrated photoluminescence (PL), time-resolved PL (TRPL) from these organic materials was measured by time-correlated single photon counting (TCSPC) technique. Doping the guest emitter DCM to the host emitter in organic dyes can make the energy transfer from the host to the guest, and then the spontaneous emission rate can be increased. Gold film coated on the sample induces the surface plasmon enhancement between the metal and the dielectric medium and the Purcell factor, obtained from the TRPL signals measured with and without the gold film, can be increased. While those of Znq:DCM and BAlq:DCM are improved with gold film, the radiative properties of Alq3:DCM are not significantly affected. For Znq:DCM coupled with gold film, PL intensity enhancement as large as 8-fold was observed and the Purcell factor was estimated to be ~2. Significant shortening of radiative lifetime was also observed for Au film-covered Znq:DCM and the corresponding radiation efficiency was estimated.

Since the discovery of luminescence from organic materials, there has been a considerable amount of efforts devoted to developing organic light emitting devices for use in display applications. Recently, organic light emitting materials also emerge as the candidate for highly efficient active media for lasers. And significant enhancement of spontaneous emission by coupling with surface plasmonic energy transfer has been demonstrated for organic materials. In this work, we studied the surface plasmon-induced enhancement of spontaneous emission and estimated the Purcell factors from three organic chelates dyes doped by 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM), Znq:DCM (2.5%), BAlq:DCM (2.5%), and Alq3:DCM (2.5%). Besides the time-integrated photoluminescence (PL), time-resolved PL (TRPL) from these organic materials was measured by time-correlated single photon counting (TCSPC) technique. Doping the guest emitter DCM to the host emitter in organic dyes can make the energy transfer from the host to the guest, and then the spontaneous emission rate can be increased. Gold film coated on the sample induces the surface plasmon enhancement between the metal and the dielectric medium and the Purcell factor, obtained from the TRPL signals measured with and without the gold film, can be increased. While those of Znq:DCM and BAlq:DCM are improved with gold film, the radiative properties of Alq3:DCM are not significantly affected. For Znq:DCM coupled with gold film, PL intensity enhancement as large as 8-fold was observed and the Purcell factor was estimated to be ~2. Significant shortening of radiative lifetime was also observed for Au film-covered Znq:DCM and the corresponding radiation efficiency was estimated.