Associative learning, a critical learning principle to improve an individual’s adaptability, has been emulated by few organic electrochemical devices. However, complicated bias schemes, high write voltages, as well as process irreversibility hinder the further development of associative learning circuits. Here, by adopting a poly(3,4-ethylenedioxythiophene):tosylate/Polytetrahydrofuran composite as the active channel, we present a non-volatile organic electrochemical transistor that shows a write bias less than 0.8 V and retention time longer than 200 min without decoupling the write and read operations. By incorporating a pressure sensor and a photoresistor, a neuromorphic circuit is demonstrated with the ability to associate two physical inputs (light and pressure) instead of normally demonstrated electrical inputs in other associative learning circuits. To unravel the non-volatility of this material, ultraviolet-visible-near-infrared spectroscopy, X-ray photoelectron spectroscopy and grazing-incidence wide-angle X-ray scattering are used to characterize the oxidation level variation, compositional change, and the structural modulation of the poly(3,4-ethylenedioxythiophene):tosylate/Polytetrahydrofuran films in various conductance states. The implementation of the associative learning circuit as well as the understanding of the non-volatile material represent critical advances for organic electrochemical devices in neuromorphic applications.

Two neutral black copolymers were prepared by employing PTTPh or PTTTh as complementary segments to supplement the absorption deficiency from PTTBT.

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In the quest for solution-processable red electrochromic material with high performance, a series of 3,6-bis­(dodecyloxy)­thieno­[3,2-b]­thiophene (DOTT)-based polymers have been designed by combining DOTT with different aromatic building blocks (bithiophene, benzene, and dimethoxybenzene) and prepared through Pd-catalyzed chemical copolymerization. Among them, the solution-processable polymer poly­(2,5-dimethoxy­phenyl-1,4-diyl-3,6-bis­(dodecyloxy)­thieno­[3,2-b]­thiophene) (P3) showed obvious yellow-green fluorescence in chloroform and demonstrated a rapid reversible switching (1.1 s/0.9 s for doping/dedoping process) between the red and bleached states. This brilliant red polymer exhibited moderate contrast (46% at 510 nm) and excellent cycling stability (in film: 78% for total amount and 63% for reduction after 12000 cycles; in device: 85.6% after 3000 cycles) which qualify it for further device fabrications. This study reveals that this polymer (P3) would be a promising high performance red electrochrome and could be a good candidate for flexible and large-scale organic electrochromic devices as well as for smart indicators or display applications.