考虑到有机薄膜晶体管( OTFT) 带隙中存在指数分布的陷阱态密度，提出了基于表面势的电流解析模型．在模型建立过程中，使用薄层电荷近似区分扩散电流和漂移电流; 采用泰勒展开来实现表面势的解析求解，得到较高的求解精度．基于变程跳跃理论，即载流子在局域态之间的热激活特征的隧穿输运机理，解释了OTFT 的转移特性和温度特性．模型计算结果与实验数据一致性好，说明该模型可适用于电路模拟器．

Proposed in this paper is a surface-potential-based drain current model for organic thin-film transistor ( OTFT) that takes into consideration the exponential distribution of the trap state density within the bandgaps. In the process of modeling,the diffusion and drift currents are approximately identified by means of the charge sheet approach. Then,a high-precision analytical solution for surface potential is presented via Taylor expansion. Moreover,the transfer and temperature characteristics of OTFT are described based on the variable-range hopping theory,i. e.,the thermally-activated tunneling mechanism of carriers between localized states. It is found that the calculation results accord well with the experimental ones,which shows that the proposed model is applicable to the circuit simulator.