Electrochemical Stability Investigations and Drug Toxicity Tests of Electrolyte-Gated Organic Field-Effect Transistors

Abstract

Electrolyte-gated organic field-effect transistors (EGOFETs) are emerging as a new frontier of organic bioelectronics, with promising applications in biosensing, pharmaceutical testing, and neuroscience. However, the limited charge carriers’ mobility and well-known environmental instability of conjugated polymers constrain the real applications of organic bioelectronics. Here, we comparatively studied the electrochemical stability of p-type conjugated polymer films in the EGOFET configuration. By combining electrochemical stability tests, morphology characterization, and EQCM-D monitoring, we find that a donor–acceptor copolymer, poly­(N-alkyldiketopyrrolo-pyrrole-dithienylthieno­[3,2-b]­thiophene) (DPP-DTT) shows improved mobility and electrochemical stability under an electrolyte, which may benefit from the ordered morphology and close alkyl side-chains’ interdigitation preventing water diffusion and ion doping during long-term operation under an electrolyte. Based on the DPP-DTT EGOFETs, we have demonstrated a low-cost drug toxicity test platform that is sensitive enough to distinguish the cytotoxicity of different chemicals. This study overall pushes forward the development of organic bioelectronics with enhanced stability and sensitivity and presents successful exploitation of EGOFET in pharmaceutical research.

In Situ Monitoring of Polaron Localization and Cell Activity with Charge Accumulation Spectroscopy

“…As the thickness of EDL is just a few Å, the large capacitive coupling enables low voltage operation (typically <1 V) of the device. [ 8,18 ] Figure 1b shows the transfer curve of a typical electrolyte‐gated pBTTT transistor with a charge carrier mobility of (0.09 ± 0.02) cm 2 V −1 s −1 , which far surpasses that of water‐gated P3HT and pentacene transistors with the mobility value reported to be in the range of 8 × 10 −3 –2 × 10 −2 cm 2 V −1 s −1 . [ 8,19 ]…”

“…[8,18] Figure 1b shows the transfer curve of a typical electrolyte-gated pBTTT transistor with a charge carrier mobility of (0.09 ± 0.02) cm 2 V −1 s −1 , which far surpasses that of watergated P3HT and pentacene transistors with the mobility value reported to be in the range of 8 × 10 −3 -2 × 10 −2 cm 2 V −1 s −1 . [8,19] Although polaron localization at the polymer-dielectric interface of solid-state FET devices has been well characterized in previous studies using charge modulation spectroscopy. [20][21][22] The charge transport property at the solid-liquid interface under strong charge-ion-dipole interactions remains unexplored.…”

“…The result suggests that the electrostatic and electrochemical operation mechanisms can coexist if the device has a permeable organic active layer, which is often the case for most organic polymeric materials. [8,29] The conditions that could trigger the transition between the electrostatic and the electrochemical operation modes may include high voltage bias, long operation duration, and electrochemical reactions occurring at the liquid-solid interface, etc.…”

“…The widely recognized material degradation and device deterioration during long‐term operation are undesirable as they complicate the translation of sensing responses in biological applications. [ 8–10 ] Although redox reactions involving holes in the organic material, oxygen and proton have been suggested to contribute to the observed performance degradation, a detailed characterization to monitor in situ the variation in molecular configuration of organic semiconductor films under liquid and study its correlation with the charge transport behavior is still lacking. Moreover, most of the available organic bioelectronic devices make use of only the electrical response of organic semiconductors, which often encounter difficulties in decouple contributions from different processes in a complex biosensing system.…”

Advances in organic micro/nanocrystals with tunable physicochemical properties

“…What's more, the periodic molecular packing mode in the micro/ nanocrystals leads to a higher mobility and regular morphology, which make them distinguish from the amorphous structures and polymers [18][19][20]. The crystal's morphology significantly affects the final performance of solid products, such as the bioavailability for pharmaceutical compounds, reactivity for catalysts, filtering and drying times [21][22][23]. As for the optoelectronics, the morphologies of the micro/nanocrystals seriously affect the performance of devices, such as the propagation modes in waveguide devices and the resonant modes in the organic solid-state lasers (OSSLs) [24][25][26][27].…”