三重态双自由基对高电子迁移率醌型有机半导体大磁阻的重要作用,Advanced Science

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三重态双自由基对高电子迁移率醌型有机半导体大磁阻的重要作用
Advanced Science ( IF 15.1 ) Pub Date : 2022-03-28 , DOI: 10.1002/advs.202201045
Chao Wang ₁ , Hua Hao ₁ , Keisuke Tajima ₁

Affiliation

基于醌式苯并[1,2-b:4,5-b']二噻吩结构合成了一种具有高半导体性能的双自由基分子。通过量子化学计算和变温电子自旋共振研究了双自由基特性。基于这种分子的二极管器件在低于 100 mT 的磁场中显示出很大的电流变化，并且强烈依赖于测量温度；随着三重态双自由基的数量在高温下增加，磁导 (MC) 值增加。结果，在 120 °C 时实现了 -19.4% 的 MC，这是迄今为止对有机分子观察到的最大负 MC。相反，基于醌式噻吩并[3,2-b]噻吩的较小的双自由基分子没有热可及的三重态显示没有MC，表明三联双自由基的重要作用。MC和三重态双自由基浓度之间的强相关性表明双自由基中的电荷传导通过自旋阻挡机制受到抑制，这可以通过超精细场的磁调制来控制。该化合物可形成高结晶度薄膜，在有机场效应晶体管中具有高单极电子传输，平均迁移率为 1.01 cm² V ^-1 s ^-1用于流延膜。

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Essential Role of Triplet Diradical Character for Large Magnetoresistance in Quinoidal Organic Semiconductor with High Electron Mobility

A diradicaloid molecule with high semiconducting performance is synthesized based on the quinoidal benzo[1,2-b:4,5-b′]dithiophene structure. The diradical character is investigated by quantum chemical calculations and variable temperature electron spin resonance. The diode devices based on this molecule show a large change in electric current in magnetic fields below 100 mT with a strong dependence on the measurement temperatures; as the population of the triplet diradicals increases at high temperatures, the magnetoconductance (MC) values increase. As a result, a MC of −19.4% is achieved at 120 °C, which is the largest negative MC observed for organic molecules to date. In contrast, a smaller diradicaloid molecule based on quinoidal thieno[3,2-b]thiophene without thermally accessible triplet state shows no MC, indicating the essential role of the triplet diradicals. The strong correlation between the MC and the triplet diradical concentrations suggests that the charge conduction in the diradicaloid is suppressed through a spin-blocking mechanism, which can be controlled through the magnetic modulation of the hyperfine fields. The compound forms high-crystallinity thin films and has high monopolar electron transport in organic field-effect transistors, with an average mobility of 1.01 cm² V⁻¹ s⁻¹ for edge-cast films.

更新日期：2022-03-28

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