High-performance n-type organic electrochemical transistors (OECTs) are essential for logic circuits and sensors. However, the performances of n-type OECTs lag far behind that of p-type ones. Conventional wisdom posits that the LUMO energy level dictates the n-type performance. Herein, we show that engineering the doped state is more critical for n-type OECT polymers. By balancing more charges to the donor moiety, we could effectively switch a p-type polymer to high-performance n-type material. Based on this concept, the polymer, P(gTDPP2FT), exhibits a record high n-type OECT performance with μC* of 54.8 F cm−1 V−1 s−1, mobility of 0.35 cm2 V−1 s−1, and response speed of τon/τoff = 1.75/0.15 ms. Calculations and comparison studies show that the conversion is primarily due to the more uniform charges, stabilized negative polaron, enhanced conformation, and backbone planarity at negatively charged states. Our work highlights the critical role of understanding and engineering polymers’ doped states.

Organic electrochemical transistors (OECTs) have shown great potential in bioelectronics and neuromorphic computing. However, the low performance of n-type OECTs impedes the construction of complementary-type circuits for low-power-consumption logic circuits and high-performance sensing. Compared with their p-type counterparts, the low electron mobility of n-type OECT materials is the primary challenge, leading to low μC* and slow response speed. Nevertheless, no successful method has been reported to address the issue. Here, we find that the charge carrier mobility of n-type OECTs can be significantly enhanced by redistributing the polarons on the polymer backbone. As a result, 1 order of magnitude higher electron mobility is achieved in a new polymer, P­(gPzDPP-CT2), with a simultaneously enhanced μC* value and faster response speed. This work reveals the important role of polaron distribution in enhancing the performance of n-type OECTs.

Two-dimensional (2D) transition metal dichalcogenides (TMDs) with tantalizing layer-dependent electronic and optical properties have emerged as a paradigm for integrated flat opto-electronic devices, but their widespread applications are hampered by challenges in deterministic fabrication with demanded shapes and thicknesses, as well as light field manipulation in such atomic-thick layers with negligible thicknesses compared to the wavelength. Here we demonstrate ultra-sensitive light field manipulation in full visible ranges based on MoS2 laser prints exfoliated with nanometric precisions. The nontrivial interfacial phase shifts stemming from the unique dispersion of MoS2 layers integrated on the metallic substrate empower an ultra-sensitive resonance manipulation up to 13.95 nm per MoS2 layer across the entire visible bands, which is up to one-order-of-magnitude larger than their counterparts. The interlayer van der Waals interactions and the anisotropic thermal conductivity of layered MoS2 films endow a laser exfoliation method for on-demand patterning MoS2 with atomic thickness precision and subwavelength feature sizes. With this, nanometric flat color prints and further amplitude-modulated diffractive components for binocular stereoscopic images can be realized in a facile and lithography-free fashion. Our results with demonstrated practicality unlock the potentials of, and pave the way for, widespread applications of emerging 2D flat optics.

To date, high-performance organic electrochemical transistors (OECTs) are almost all based on conjugated polymers. Small molecules can be synthesized with high purity without batch-to-batch variations. However, small molecules require highly crystalline films and good molecular packings to achieve high charge carrier mobilities. Such features make their films unsuitable for ion diffusion or make their molecular packing distorted due to ion diffusion, resulting in poor ion/charge carrier transport properties and slow response speed. Herein, it is proposed to construct small-molecule-based supramolecular polymers to address these issues. A molecule, namely TDPP-RD-G7 is designed, which exhibits J-type self-assembling behaviors and can form supramolecular polymers in solution and conjugated-polymer-like networks in solid state. More importantly, the porous supramolecular polymer networks allow fast ion diffusion and greatly increase the device response speeds. As a result, the TDPP-RD-G7 exhibits record fast response speeds (τ on /τ off ) of 10.5/0.32 ms with high figure-of-merit (µC*) of 5.88 F cm −1 V −1 s −1 in small-molecule OECTs. This work reveals the possible reasons that hinder the response speeds in small-molecule OECTs and demonstrates a new "supramolecular polymer" approach to high-performance and fast-response small-molecule-based OECTs.

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