This study investigates the gate stress-induced mobility discrepancy in p-type single-crystal organic field-effect transistors (OFETs) on an octyltrichlorosilane (OTS)-modified SiO₂/Si substrate. During measurements in atmosphere, anti-clockwise hysteresis was observed in the transfer curve, and the mobility calculated from the forward sweep was smaller than that calculated from the reverse sweep. Hysteresis has often been observed for OFETs but the mobility discrepancy has not been clearly understood. We formulated a “fast trapping vs. slow detrapping” model and suggested that the mobility values calculated from the reverse sweep represent the intrinsic property of the material. To verify the validity of this model, we investigated mobility anisotropy of an air-stable organic semiconductor, 2,7-bis(4-methoxyphenyl)benzo[b]benzo[4,5]thieno[2,3-d]thiophene (DBOP-BTBT). By measuring the single-crystal OFET characteristics of many crystals with different orientations, we observed anisotropic hole mobility calculated from the reverse sweep. The mobility along the b-axis, which corresponds to the π-π stacking direction, was 13.9 cm² V⁻¹ s⁻¹, and that along the a-axis was 6.2 cm² V⁻¹ s⁻¹. However, we did not see clear anisotropy when mobility was calculated from the forward sweep due to a variation in the data. The threshold voltage from the reverse and the forward sweeps showed isotropic characteristics within the range from −60 to −70 V and from −50 to −60 V, respectively. These results indicate that the numbers of filled traps were different between the reverse and the forward sweeps at the interface, and confirm the validity of our model.

本研究调查了在辛基三氯硅烷（OTS）改性的SiO ₂上p型单晶有机场效应晶体管（OFET）中栅极应力引起的迁移率差异/ Si基板。在大气中进行测量时，在传输曲线中观察到了逆时针方向的磁滞，并且从前向扫描计算出的迁移率小于从后向扫描计算出的迁移率。经常观察到OFET的滞后现象，但尚未清楚地了解迁移率差异。我们制定了“快速捕集与慢速捕集”模型，并建议通过反向扫描计算出的迁移率值代表了材料的固有特性。为了验证该模型的有效性，我们研究了空气稳定的有机半导体2,7-双（4-甲氧基苯基）苯并[ b ]苯并[4,5]噻吩并[2,3- d ]的迁移率各向异性]噻吩（DBOP-BTBT）。通过测量许多具有不同取向的晶体的单晶OFET特性，我们观察到了由反向扫描计算出的各向异性空穴迁移率。沿迁移率b -轴，其对应于π-π堆叠方向，是13.9厘米²  V ^-1 小号^-1，和沿一个轴为6.2厘米²  V ^-1 小号^-1。但是，由于数据变化，从前向扫描计算迁移率时，我们没有看到明显的各向异性。来自反向扫描和正向扫描的阈值电压分别显示出从-60到-70 V和从-50到-60 V的各向同性特性。这些结果表明，在界面的反向扫描和正向扫描之间，填充陷阱的数量是不同的，并证实了我们模型的有效性。