Chen Chen,Haibao Ma,Kaiqing Lu,Xiaoxuan Zhang,Baiqiao Yue,Ce Song,Pochong Huang,Haifeng Cheng,Yue Lin
Controlling the microstructure of semiconducting polymers is critical for optimizing thermoelectric performance, yet remains challenging, requiring complex processing techniques like alignment. In this study, a straightforward strategy is introduced to enhance the thermoelectric properties of semi-crystalline polymer films by incorporating minimal amounts of nucleating agents, a method widely used in traditional polymer industries. By blending less than 1 wt% of N,N′-(1,4-phenyl)diisonicotinamide (PDA) into poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT-C14), controlled modulation of crystallization behavior is achieved, resulting in reduced structural disorder and enhanced charge carrier mobility. Systematic investigations reveal that an optimal PDA loading of 0.9 wt% increases the crystallization degree by 45% compared to pristine PBTTT-C14 films. Under these optimized conditions, the PDA-modified PBTTT-C14 films exhibit a maximum electrical conductivity of 1,894 S cm −1 and a maximum power factor of 176 µW m −1 K −2 , showing improvements of 96% and 433%, respectively, over doped pristine PBTTT-C14 films. These gains are attributed to the synergistic effects of polymer chain extension and reduced grain boundary resistance, which collectively enhance charge transport efficiency. Additionally, ion exchange doping is found to maintain a high charge carrier concentration while preserving the crystallinity introduced by PDA, paving the way for advanced thermoelectric materials and next-generation polymer-based electronics.
Organic near-infrared (NIR) photodetectors have attracted considerable interest as candidates for flexible, lightweight, and low-cost optoelectronic technologies. However, achieving efficient NIR absorption and high photodetection sensitivity simultaneously remains a significant challenge for most organic semiconductor systems. Here, a high-performance hybrid organic phototransistor is developed by combining a PBTTT-C 14 /F4-TCNQ donor–acceptor charge-transfer complex with monolayer graphene. Strong intermolecular charge-transfer interactions generate low-energy electronic transitions, resulting in broadband optical absorption spanning 400–1300 nm. Meanwhile, the incorporation of graphene provides an efficient transport pathway for photogenerated carriers and promotes charge separation, thereby enhancing photoconductive gain. As a result, the hybrid device exhibits excellent NIR photodetection performance under 800 nm illumination, delivering a responsivity of 1.67 × 10 5 A/W, a detectivity of 3.26 × 10 12 Jones, and an external quantum efficiency of 2.92% × 10 7 %. Notably, a measurable photoresponse is maintained even under extremely weak irradiation, demonstrating outstanding sensitivity toward low-intensity optical signals. In addition, the device shows stable switching behavior with millisecond-scale response characteristics. Integration into a phototransistor array further enables spatially resolved NIR imaging. These results highlight the effectiveness of integrating charge-transfer complexes with two-dimensional conductive materials and provide a viable strategy for next-generation high-gain organic infrared sensing and imaging applications.
Two-dimensional (2D) crystals of conjugated polymers (2DCCPs) have attracted significant attention in the past few decades due to their superior and intriguing optoelectronic properties. With the increase in brain-inspired neuromorphic computing, 2DCCPs have also been employed in the construction of synaptic devices because they offer clear advantages of easy integration, high stability, long–range order and no biological rejection. However, pursuing controllable strategies to obtain high-quality and large-scale 2DCCPs remains a challenge on account of their intrinsic complex structures. Herein, we present a universal methodology to grow centimeter-scale 2DCCPs in a controlled manner within minutes by selecting an appropriate growth-assisting solvent and surfactant. The thickness of the as-produced 2DCCPs was down to two molecular layers. The photonic synaptic transistors based on the as-grown 2DCCPs could perform typical synaptic functions, including short-term plasticity, paired-pulse facilitation, long-term plasticity and spike intensity-dependent plasticity. The transistor was also proven to have potential application as a high-pass filter. This methodology shows great potential to be expanded to many other polymer systems and opens new pathways for large-area integrated wireless communication systems and artificial visual systems.
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