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In the realm of flexible optoelectronic devices, intrinsic flexible fully π‐conjugated polymers (FπCPs) assume a pivotal role owing to their concurrent intrinsic viscoelasticity and robust optoelectronic properties. As flexible devices are destined to encounter diverse stress environments, the selection of functional materials based on mechanical requirements becomes imperative. Here, VPERD assessment system is introduced to scrutinize the mechanical properties of side‐chain plasticizing FπCPs. The acronym VPERD encapsulates five key aspects of mechanical characteristics, namely viscidity (V), plasticity (P), elasticity (E), rigidity (R), and ductility (D). The mechanical characteristics of FπCPs are tuned through the control of flexible chain density (FCD). Enhancing FCD induces superior chain softness, favorable solubility, and heightened viscoplasticity. Through precise regulation of FCD and thoughtful structural design, freestanding FπCPs nano‐films exhibit a remarkable maximum fracture strain of ≈50%. Deep‐blue flexible polymer light‐emitting diodes (PLEDs) reveal that maintaining FCD at ≈50% achieves a balance between mechanical and optoelectronic properties. The stretched films after strain fatigue both show that mild strain is conducive to enhancing the efficiency of FπCPs films and devices. According to VPERD assessment system, the prerequisite for achieving intrinsically flexible FπCPs lies in controlling the degree of side‐chain internal plasticization through the tuning of FCD. [ABSTRACT FROM AUTHOR]

High‐performing n‐type polymers are crucial for the advance of organic electronics field, however strong electron‐deficient building blocks with optimized physicochemical properties for constructing them are still limited. The imide‐functionalized polycyclic aromatic hydrocarbons (PAHs) with extended π‐conjugated framework, high electron deficiency and good solubility serve as promising candidates for developing high‐performance n‐type polymers. Among the PAHs, phenanthrene (PhA) features a well‐delocalized aromatic π‐system with multiple modifiable active sites. However, the PhA‐based imides are seldom studied, mainly attributed to the synthetic challenge. Herein, we report two functionalized PhAs, CPOI and CPCNI, by simultaneously incorporating imide with carbonyl or dicyanomethylene onto PhA. Notably, the dicyanomethylene‐modified CPCNI exhibits a well stabilized LUMO energy level (−3.84 eV), attributed to the synergetic inductive effect from imide and cyano groups. Subsequently, based on CPOI and CPCNI, two polymers PCPOI‐Tz and PCPCNI‐Tz were developed. Applied to organic thin‐film transistors, owing to the strong electron‐deficiency of CPCNI, polymer PCPCNI‐Tz shows an improved electron mobility and largely decreased threshold voltage compared with PCPOI‐Tz. This work affords two structurally novel electron‐deficient building blocks and highlights the effectiveness of dual functionalization of PhAs with strong electron‐withdrawing groups for devising n‐type polymers. [ABSTRACT FROM AUTHOR]

High‐performing n‐type polymers are crucial for the advance of organic electronics field, however strong electron‐deficient building blocks with optimized physicochemical properties for constructing them are still limited. The imide‐functionalized polycyclic aromatic hydrocarbons (PAHs) with extended π‐conjugated framework, high electron deficiency and good solubility serve as promising candidates for developing high‐performance n‐type polymers. Among the PAHs, phenanthrene (PhA) features a well‐delocalized aromatic π‐system with multiple modifiable active sites. However, the PhA‐based imides are seldom studied, mainly attributed to the synthetic challenge. Herein, we report two functionalized PhAs, CPOI and CPCNI, by simultaneously incorporating imide with carbonyl or dicyanomethylene onto PhA. Notably, the dicyanomethylene‐modified CPCNI exhibits a well stabilized LUMO energy level (−3.84 eV), attributed to the synergetic inductive effect from imide and cyano groups. Subsequently, based on CPOI and CPCNI, two polymers PCPOI‐Tz and PCPCNI‐Tz were developed. Applied to organic thin‐film transistors, owing to the strong electron‐deficiency of CPCNI, polymer PCPCNI‐Tz shows an improved electron mobility and largely decreased threshold voltage compared with PCPOI‐Tz. This work affords two structurally novel electron‐deficient building blocks and highlights the effectiveness of dual functionalization of PhAs with strong electron‐withdrawing groups for devising n‐type polymers. [ABSTRACT FROM AUTHOR]

Developing low‐cost and high‐performance n‐type polymer semiconductors is essential to accelerate the application of organic thermoelectrics (OTEs). To achieve this objective, it is critical to design strong electron‐deficient building blocks with simple structure and easy synthesis, which are essential for the development of n‐type polymer semiconductors. Herein, we synthesized two cyano‐functionalized highly electron‐deficient building blocks, namely 3,6‐dibromopyrazine‐2‐carbonitrile (CNPz) and 3,6‐Dibromopyrazine‐2,5‐dicarbonitrile (DCNPz), which feature simple structures and facile synthesis. CNPz and DCNPz can be obtained via only one‐step reaction and three‐step reactions from cheap raw materials, respectively. Based on CNPz and DCNPz, two acceptor–acceptor (A–A) polymers, P(DPP‐CNPz) and P(DPP‐DCNPz) are successfully developed, featuring deep‐positioned lowest unoccupied molecular orbital (LUMO) energy levels, which are beneficial to n‐type organic thin‐film transistors (OTFTs) and OTEs performance. An optimal unipolar electron mobility of 0.85 and 1.85 cm2 V−1 s−1 is obtained for P(DPP‐CNPz) and P(DPP‐DCNPz), respectively. When doped with N‐DMBI, P(DPP‐CNPz) and P(DPP‐DCNPz) show high n‐type electrical conductivities/power factors of 25.3 S cm−1/41.4 μW m−1 K−2, and 33.9 S cm−1/30.4 μW m−1 K−2, respectively. Hence, the cyano‐functionalized pyrazine CNPz and DCNPz represent a new class of structurally simple, low‐cost and readily accessible electron‐deficient building block for constructing n‐type polymer semiconductors. [ABSTRACT FROM AUTHOR]

Developing low‐cost and high‐performance n‐type polymer semiconductors is essential to accelerate the application of organic thermoelectrics (OTEs). To achieve this objective, it is critical to design strong electron‐deficient building blocks with simple structure and easy synthesis, which are essential for the development of n‐type polymer semiconductors. Herein, we synthesized two cyano‐functionalized highly electron‐deficient building blocks, namely 3,6‐dibromopyrazine‐2‐carbonitrile (CNPz) and 3,6‐Dibromopyrazine‐2,5‐dicarbonitrile (DCNPz), which feature simple structures and facile synthesis. CNPz and DCNPz can be obtained via only one‐step reaction and three‐step reactions from cheap raw materials, respectively. Based on CNPz and DCNPz, two acceptor–acceptor (A–A) polymers, P(DPP‐CNPz) and P(DPP‐DCNPz) are successfully developed, featuring deep‐positioned lowest unoccupied molecular orbital (LUMO) energy levels, which are beneficial to n‐type organic thin‐film transistors (OTFTs) and OTEs performance. An optimal unipolar electron mobility of 0.85 and 1.85 cm2 V−1 s−1 is obtained for P(DPP‐CNPz) and P(DPP‐DCNPz), respectively. When doped with N‐DMBI, P(DPP‐CNPz) and P(DPP‐DCNPz) show high n‐type electrical conductivities/power factors of 25.3 S cm−1/41.4 μW m−1 K−2, and 33.9 S cm−1/30.4 μW m−1 K−2, respectively. Hence, the cyano‐functionalized pyrazine CNPz and DCNPz represent a new class of structurally simple, low‐cost and readily accessible electron‐deficient building block for constructing n‐type polymer semiconductors. [ABSTRACT FROM AUTHOR]