The development of n-type organic electrochemical transistors (OECTs) lags far behind their p-type counterparts. In order to address this dilemma, we report here two new fused bithiophene imide dimer (f-BTI2)-based n-type polymers with abranched methyl end-capped glycol side chain, which exhibit good solubility,l ow-lying LUMO energy levels,f avorable polymer chain orientation, and efficient ion transport property, thus yielding aremarkable OECT electron mobility (m e )ofup to % 10 À2 cm 2 V À1 s À1 and volumetric capacitance (C*) as high as 443 Fcm À3 ,simultaneously.Asaresult, the f-BTI2TEG-FTbased OECTs deliver ar ecord-high maximum geometrynormalized transconductance of 4.60 Scm À1 and am aximum mC* product of 15.2 Fcm À1 V À1 s À1 .T he mC* figure of merit is more than one order of magnitude higher than that of the stateof-the-art n-type OECTs.T he emergence of f-BTI2TEG-FT brings an ew paradigm for developing high-performance ntype polymers for low-power OECT applications.
Charge carrier nonradiative recombination (NRR) caused by interface defects and nonoptimal energy level alignment is the primary factor restricting the performance improvement of perovskite solar cells (PSCs). Interfacial modification is a vital strategy to restrain NRR and enable high-performance PSCs. We report here two interfacial materials, PhI-TPA and BTZI-TPA, consisting of phthalimide and a 2,1,3-benzothiadiazole-5,6-dicarboxylicimide core, respectively. The difunctionalized BTZI-TPA with imide and thiadiazole shows higher hole mobility, better aligned energy levels, and stronger interaction with uncoordinated Pb2+ on the perovskite surface, suppressing NRR and carrier accumulation at the interface of perovskite/spiro-OMeTAD and yielding enhanced open-circuit voltage and fill factor. Consequently, the PSC based on BTZI-TPA delivers a high efficiency of 24.06% with an excellent fill factor of 83.10%, superior to that (21.47%) of the reference cell without an interfacial layer, and 21.45% efficiency for the device with a scaled-up area (1.00 cm2). These results underscore the potential of imide and thiadiazole groups in developing interfacial layers with strong passivation capability, effective charge transport property, and fine-tuned energetics for stable and efficient PSCs.
Developing organic solar cells (OSCs) based on a ternary active layer is one of the most effective approaches to maximize light harvesting and improve their photovoltaic performance. However, this strategy meets very limited success in all‐polymer solar cells (all‐PSCs) due to the scarcity of narrow bandgap polymer acceptors and the challenge of morphology optimization. In fact, the power conversion efficiencies (PCEs) of ternary all‐PSCs even lag behind binary all‐PSCs. Herein, highly efficient ternary all‐PSCs are realized based on an ultranarrow bandgap (ultra‐NBG) polymer acceptor DCNBT‐TPC, a medium bandgap polymer donor PTB7‐Th, and a wide bandgap polymer donor PBDB‐T. The optimized ternary all‐PSCs yield an excellent PCE of 12.1% with a remarkable short‐circuit current density of 21.9 mA cm−2. In fact, this PCE is the highest value reported for ternary all‐PSCs and is much higher than those of the corresponding binary all‐PSCs. Moreover, the optimized ternary all‐PSCs show a photostability with ≈68% of the initial PCE retained after 400 h illumination, which is more stable than the binary all‐PSCs. This work demonstrates that the utilization of a ternary all‐polymer system based on ultra‐NBG polymer acceptor blended with compatible polymer donors is an effective strategy to advance the field of all‐PSCs.
All-polymer solar cells (all-PSCs) have attracted considerable attention owing to their pronounced advantages of excellent mechanical flexibility/stretchability and greatly enhanced device stability as compared to other types of organic solar cells (OSCs). Thanks to the extensive research efforts dedicated to the development of polymer acceptors, all-PSCs have achieved remarkable improvement of photovoltaic performance, recently. This review summarizes the recent progress of polymer acceptors based on the key electron-deficient building blocks, which include bithiophene imide (BTI) derivatives, boron-nitrogen coordination bond (B ! N)-incorporated (hetero)arenes, cyano-functionalized (hetero)arenes, and fused-ring electron acceptors (FREAs). In addition, single-component-based all-PSCs are also briefly discussed. The structure-property correlations of polymer acceptors are elaborated in detail. Finally, we offer our insights into the development of new electron-deficient building blocks with further optimized properties and the polymers built from them for efficient all-PSCs.
The first water-soluble biphen[4]arene containing eight carboxylato moieties (carboxylatobiphen[4]arene, CBP4) has been synthesized. Selective molecular recognition of acetylcholine (ACh) against choline (Ch) and betaine (Bt) and pH-responsive host-guest complexation in aqueous media are described.
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