[14p-311-1~19] 12.2 Characterization and Materials Physics

[14p-311-1] Coexistence of ultra-long spin lifetime and band-like transport in organic single-crystal

〇Junto Tsurumi¹, Takayoshi Kubo¹, Chikahiko Mitsui¹, Toshihiro Okamoto^1,2, Shun Watanabe^1,2, Jun Takeya¹ (1.The Univ. of Tokyo, 2.JST PRESTO)

Keywords:organic semiconductors, spin relaxation mechanism

Spin and charge momentum relaxation mechanism has been argued among organic semiconductors with various methods, devices, and materials. However, little is known in organic single-crystalline semiconductors because it has been hard to obtain an ideal organic crystal with an excellent crystallinity and controllability required for accurate measurements. By using more than 1-inch sized single crystals which are fabricated via contentious edge-casting method developed by our group, we have successfully demonstrated a simultaneous determination of spin and momentum relaxation time for gate-induced charges of 3,11-didecyldinaphtho[2,3-d:2’,3’-d’]benzo[1,2-b:4,5-b’]dithiophene, by combining electron spin resonance (ESR) and Hall effect measurements. The obtained temperature dependences of spin and momentum relaxation times are in good agreement in terms of power law with a factor of approximately -2.85. It is concluded that Elliott-Yafet spin relaxation mechanism can be dominant at room temperature regime (4 – 300 K). Probing characteristic time scales such as spin-lattice, spin-spin, and momentum relaxation times, demonstrated in the present work, would be a powerful tool to elucidate fundamental spin and charge transport mechanisms.