Directly Unveiling the Energy Transfer Dynamics between Alq3 Molecules and Si by Ultrafast Optical Pump-Probe Spectroscopy

Yu-Chan Tai; Wen-Yen Tzeng; Jhen-Dong Lin; Yi-Hou Kuo; Fu-Xiang Rikudo Chen; Ruei-Jhe Tu; Ming-Yang Huang; Shyh-Shii Pai; Nick Weihan Chang; Sheng-Yang Tseng; Chi Chen; Chun-Liang Lin; Atsushi Yabushita; Shun-Jen Cheng; Chih-Wei Luo

doi:10.1021/acs.nanolett.3c03251

Directly Unveiling the Energy Transfer Dynamics between Alq₃ Molecules and Si by Ultrafast Optical Pump-Probe Spectroscopy

Nano Lett. 2023 Nov 22;23(22):10490-10497. doi: 10.1021/acs.nanolett.3c03251. Epub 2023 Nov 1.

Authors

Yu-Chan Tai¹, Wen-Yen Tzeng^{1

2}, Jhen-Dong Lin¹, Yi-Hou Kuo¹, Fu-Xiang Rikudo Chen¹, Ruei-Jhe Tu¹, Ming-Yang Huang¹, Shyh-Shii Pai³, Nick Weihan Chang³, Sheng-Yang Tseng³, Chi Chen⁴, Chun-Liang Lin¹, Atsushi Yabushita¹, Shun-Jen Cheng¹, Chih-Wei Luo^{1

5

6

7

8}

Affiliations

¹ Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan.
² Department of Electronic Engineering, National Formosa University, Yunlin 632, Taiwan.
³ FAB 12B, Taiwan Semiconductor Manufacturing Company, Ltd., Hsinchu 300, Taiwan.
⁴ Research Center for Applied Sciences, Academia Sinica, Taipei 115, Taiwan.
⁵ Institute of Physics and Center for Emergent Functional Matter Science, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan.
⁶ National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan.
⁷ Taiwan Consortium of Emergent Crystalline Materials (TCECM), National Science and Technology Council, Taipei 115, Taiwan.
⁸ Department of Physics, University of Washington, Seattle, Washington 98195, United States.

PMID: 37909686
DOI: 10.1021/acs.nanolett.3c03251

Abstract

The energy transfer (ET) between organic molecules and semiconductors is a crucial mechanism for enhancing the performance of semiconductor-based optoelectronic devices, but it remains undiscovered. Here, ultrafast optical pump-probe spectroscopy was utilized to directly reveal the ET between organic Alq₃ molecules and Si semiconductors. Ultrathin SiO₂ dielectric layers with a thickness of 3.2-10.8 nm were inserted between Alq₃ and Si to prevent charge transfer. By means of the ET from Alq₃ to Si, the SiO₂ thickness-dependent relaxation dynamics of photoexcited carriers in Si have been unambiguously observed on the transient reflectivity change (ΔR/R) spectra, especially for the relaxation process on a time scale of 200-350 ps. In addition, these findings also agree with the results of our calculation in a model of long-range dipole-dipole interactions, which provides critical information for developing future optoelectronic devices.

Keywords: excitonic sensitization; nonradiative energy transfer; silicon; time-resolved spectroscopy.