Charge Transport Behavior and Ultrasensitive Photoresponse Performance of Exfoliated F₁₆CuPc Nanoflakes

Air-stable, photosensitive copper hexadecafluorophthalocyanine (F₁₆CuPc) is a promising n-type semiconductor for organic electronics and optoelectronics. However, the performance of F₁₆CuPc-based devices is significantly limited by the poor crystallinity of thin films. Here, the charge transport and electrical contact behavior of F₁₆CuPc nanoflakes, mechanically exfoliated from needle-like bulk single crystals, are probed by analyzing the temperature-dependent carrier mobility and conductance, where the multiple-trap/release- and band-like transport mechanism govern the charge transport at different temperature ranges and carrier densities. F₁₆CuPc nanoflake-based field effect transistors (FETs) exhibit high on-state current and ON/OFF ratio, one-order magnitude higher than those of reported F₁₆CuPc nanowires, thin films, and nanoribbons. Besides, F₁₆CuPc nanoflake-based phototransistors exhibit attractive photoresponse performance in the spectral range of 300–750 nm even at quite low operating source–drain voltage (1 V), with maximum photoresponsivity of 19 A W⁻¹, detectivity of 8 × 10¹² Jones, and fast response speed of 36 ms, which is attributed to the single-crystalline characteristic of nanoflakes, and the resultant efficiently exciton diffusion and charge transport. The work demonstrates that 2D organic nanoflakes with single-crystalline feature will be promising candidates for flexible electronic and optoelectronic devices.