Fluorinated Alcohol-Processed N‑Type Organic Electrochemical Transistor with High Performance and Enhanced Stability

Tuning the film morphology and aggregated structure is a vital means to improve the performance of the mixed ionic–electronic conductors in organic electrochemical transistors (OECTs). Herein, three fluorinated alcohols (FAs), including 2,2,2-trifluoroethanol (TFE), 1,1,1,3,3,3-hexafluoroisopropanol (HFIP), and perfluoro-tert-butanol (PFTB), were employed as the alternative solvents for engineering the n-type small-molecule active layer gNR. Remarkedly, an impressive μC* of 5.12 F V–1 cm–1 s–1 and a normalized transconductance of 1.216 S cm–1 are achieved from the HFIP-fabricated gNR OECTs, which is three times higher than that of chloroform. The operational stability has been significantly enhanced by the FA-fabricated devices. Such enhancements can be ascribed to the aggregation-induced structural ordering by FAs during spin coating, which optimizes the microstructure of the films for a better mixed ion and electron transport. These results prove the huge research potential of FAs to improve OECT materials’ processability, device performance, and stability, therefore promoting practical bio-applications

A Thieno[2,3‑<i>b</i>]pyridine-Flanked Diketopyrrolopyrrole Polymer as an n‑Type Polymer Semiconductor for All-Polymer Solar Cells and Organic Field-Effect Transistors

A novel fused heterocycle-flanked diketopyrrolopyrrole (DPP) monomer, thieno­[2,3-<i>b</i>]­pyridine diketopyrrolopyrrole (TPDPP), was designed and synthesized. When copolymerized with 3,4-difluorothiophene using Stille coupling polymerization, the new polymer pTPDPP-TF possesses a highly planar conjugated polymer backbone due to the fused thieno­[2,3-<i>b</i>]­pyridine flanking unit that effectively alleviates the steric hindrance with both the central DPP core and the 3,4-difluorothiophene repeat unit. This new polymer exhibits a high electron affinity (EA) of −4.1 eV and was successfully utilized as an n-type polymer semiconductor for applications in organic field-effect transistors (OFETs) and all polymer solar cells. A promising n-type charge carrier mobility of 0.1 cm² V^–1 s^–1 was obtained in bottom-contact, top-gate OFETs, and a power conversion efficiency (PCE) of 2.72% with a high open-circuit voltage (<i>V</i>_OC) of 1.04 V was achieved for all polymer solar cells using PTB7-Th as the polymer donor

Amorphous Tin Oxide as a Low-Temperature-Processed Electron-Transport Layer for Organic and Hybrid Perovskite Solar Cells

Chemical bath deposition (CBD) of tin oxide (SnO₂) thin films as an electron-transport layer (ETL) in a planar-heterojunction n–i–p organohalide lead perovskite and organic bulk-heterojunction (BHJ) solar cells is reported. The amorphous SnO₂ (a-SnO₂) films are grown from a nontoxic aqueous bath of tin chloride at a very low temperature (55 °C) and do not require postannealing treatment to work very effectively as an ETL in a planar-heterojunction n–i–p organohalide lead perovskite or organic BHJ solar cells, in lieu of the commonly used ETL materials titanium oxide (TiO₂) and zinc oxide (ZnO), respectively. Ultraviolet photoelectron spectroscopy measurements on the glass/indium–tin oxide (ITO)/SnO₂/methylammonium lead iodide (MAPbI₃)/2,2′,7,7′-tetrakis­(<i>N</i>,<i>N</i>-di-<i>p</i>-methoxyphenylamine)-9,9′-spirobifluorene device stack indicate that extraction of photogenerated electrons is facilitated by a perfect alignment of the conduction bands at the SnO₂/MAPbI₃ interface, while the deep valence band of SnO₂ ensures strong hole-blocking properties. Despite exhibiting very low electron mobility, the excellent interfacial energetics combined with high transparency (<i>E</i>_gap,optical > 4 eV) and uniform substrate coverage make the a-SnO₂ ETL prepared by CBD an excellent candidate for the potentially low-cost and large-scale fabrication of organohalide lead perovskite and organic photovoltaics

Hybrid Rylene Arrays via Combination of Stille Coupling and C–H Transformation as High-Performance Electron Transport Materials

Hybrid rylene arrays have been prepared via a combination of Stille coupling and C–H transformation. The ability to extend the π system along the equatorial axis of rylenes not only leads to broadened light absorption but also increases the electron affinity, which can facilitate electron injection and transport with ambient stability