Lowering the Contact Barriers of 2D Organic F16CuPc Field-Effect Transistors by Introducing Van der Waals Contacts

2D organic crystals exhibit efficient charge transport and field-effect characteristics, making them promising candidates for high-performance nanoelectronics. However, the strong Fermi level pinning (FLP) effect and large Schottky barrier between organic semiconductors and metals largely limit device performance. Herein, by carrying out temperature-dependent transport and Kelvin probe force microscopy measurements, it is demonstrated that the introducing of 2D metallic 1T-TaSe2 with matched band-alignment as electrodes for F16CuPc nanoflake filed-effect transistors leads to enhanced field-effect characteristics, especially lowered Schottky barrier height and contact resistance at the contact and highly efficient charge transport within the channel, which are attributed to the significantly suppressed FLP effect and appropriate band alignment at the nonbonding van der Waals (vdW) hetero-interface. Moreover, by taking advantage of the improved contact behavior with 1T-TaSe2 contact, the optoelectronic performance of F16CuPc nanoflake-based phototransistor is drastically improved, with a maximum photoresponsivity of 387 A W-1 and detectivity of 3.7 x 10(14) Jones at quite a low V-ds of 1 V, which is more competitive than those of the reported organic photodetectors and phototransistors. The work provides an avenue to improve the electrical and optoelectronic properties of 2D organic devices by introducing 2D metals with appropriate work function for vdW contacts.

Automated summary

Two-dimensional organic crystals show promising potential for high-performance nanoelectronics, but are limited by strong Fermi level pinning effects and large Schottky barriers between organic semiconductors and metals. By introducing 2D metallic 1T-TaSe2 with matched band-alignment as electrodes, enhanced field-effect characteristics and improved optoelectronic performance of F16CuPc nanoflake-based phototransistors are achieved, surpassing reported organic photodetectors and phototransistors.