Scanning modulated photocurrent microscopy by means of chopped red laser light for local excitation is employed in organic field-effect transistors having pentacene as active layer. The spatial modulated photoresponse presents a gradual increase from the source-to drain-side with increasing the negative gate-source voltage and undergoes enhancement under additional full device blue bias-bandgap illumination. The electric field-assisted exciton dissociation mechanism alone cannot explain the photoresponse enhancement under blue bias-light. This enhancement can be explained by considering that the electrons from the laser light-created triplet excitons have a large probability to be transferred to trapped holes accumulated at the pentacene-insulator interface creating mobile holes. In the framework of this interpretation, an increased local photoresponse reveals the channel region with upwards band bending and accumulated trapped holes from holes injected and extra holes created in case where an additional blue bias-light bandgap excitation is employed. Taking advantage of this property, the gradual increase of the spatial photoresponse along the channel, observed during turning-on the transistor with increasing the negative gate voltage, can be used to visualize the growing accumulation channel region from the source-to drain-side against the pinch-off depletion region. Moreover, the spatial photoresponse changes observed during transition from the linear to the saturation regime with increasing the negative drain voltage, can be used to monitor the suppression of the accumulation region and the increase of the electric field in the drain-side.

在具有并五苯作为有源层的有机场效应晶体管中，采用通过斩波红色激光进行局部激发的扫描调制光电流显微镜。随着负栅极-源极电压的增加，空间调制的光响应呈现出从源极到漏极侧的逐渐增加，并且在附加的全器件蓝色偏置带隙照明下经历了增强。电场辅助的激子离解机制本身不能解释在蓝色偏光下的光响应增强。可以通过考虑来自激光产生的三重态激子的电子有很大的可能性转移到在并五苯-绝缘体界面处积累的陷阱空穴中形成移动空穴的可能性来解释这种增强。在这种解释的框架内，增大的局部光响应揭示了带向上弯曲的沟道区域，以及在采用额外的蓝色偏光带隙激发的情况下，注入的空穴和所产生的额外空穴所累积的陷获空穴。利用此特性，在开启晶体管期间，随着负栅极电压的增加，观察到沿着沟道的空间光响应的逐渐增加，可以用来可视化从源极到漏极侧不断增长的累积沟道区域。夹断耗尽区。此外，在从线性到饱和状态的过渡过程中观察到的空间光响应变化随着负漏极电压的增加而变化，可以用来监视累积区的抑制和漏极侧电场的增加。