Ultrafast Dynamics in between Alq3 Molecules and Bulk Silicon
Yu Chan Tai1*, Wen Yen Tzeng1, Jhen Dong Lin1, Ming Yang Huang1, Shun Jen Cheng1, Chun Liang Lin1, Chih Wei Luo1
1Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu, Taiwan
* Presenter:Yu Chan Tai, email:brianyjtai1994@gmail.com
Energy dynamics of quasiparticles in between adsorbates and substrates is an issue for the development of energy-conversion devices. In this study, the ultrafast dynamics of quasiparticles in organic tris-(8-hydroxyquinoline) aluminum (Alq3) molecules were revealed by optical-pump optical-probe spectroscopy. We successfully observed an enhanced decay rate in time-resolved differential reflectivity of bulk silicon under the existence of Alq3 photoluminescence excited by ultrashort laser pulses. Additionally, the decay rate of quasiparticles in Si substrates was significantly enhanced by the existence of Alq3 molecules on the surface of Si. This result is confirmed by comparing two different time-resolved differential reflectivities of Alq3 molecules deposited on copper and sapphire substrates. Comparing with the results of Alq3 molecules on copper and sapphire substrates, we found that a relatively persistent electric field could accelerate the recombination process of Si from Alq3 molecules, which is caused by the energy transfer between Alq3 molecules and Si.

Keywords: Alq3 Molecules, Silicon, Ultrafast Dynamics