Polarization Raman Imaging of Organic Monolayer Islands for Crystal Orientation Analysis

Toki Moriyama; Takayuki Umakoshi; Yoshiaki Hattori; Koki Taguchi; Prabhat Verma; Masatoshi Kitamura

doi:10.1021/acsomega.0c06313

Polarization Raman Imaging of Organic Monolayer Islands for Crystal Orientation Analysis

ACS Omega. 2021 Mar 31;6(14):9520-9527. doi: 10.1021/acsomega.0c06313. eCollection 2021 Apr 13.

Authors

Toki Moriyama¹, Takayuki Umakoshi^{1

2}, Yoshiaki Hattori³, Koki Taguchi¹, Prabhat Verma¹, Masatoshi Kitamura³

Affiliations

¹ Department of Applied Physics, Osaka University, 2-1, Yamadaoka, Suita, Osaka 565-0871, Japan.
² PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.
³ Department of Electrical and Electronic Engineering, Kobe University, 1-1, Rokkodai-cho, Nada, Kobe 657-8501, Japan.

Abstract

An organic semiconductor film made of diphenyl derivative dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (DPh-DNTT) has high carrier mobility. However, this mobility may be greatly affected by the crystal orientation of the DPh-DNTT's first layer. Polarization Raman microscopy is widely used to quantitatively analyze the molecular orientation, and thus holds great potential as a powerful tool to investigate the crystal orientation of monolayer DPh-DNTT with high spatial resolution. In this study, we demonstrate polarization Raman imaging of monolayer DPh-DNTT islands for crystal orientation analysis. We found that the DPh-DNTT sample indicated a strong dependence of the Raman intensity on the incident polarization direction. Based on the polarization dependence, we developed an analytical method of determining the crystal orientation of the monolayer DPh-DNTT islands and experimentally confirmed that our technique was highly effective at imaging the islands' crystal orientation with a spatial resolution of a few hundred nanometers.