Semiconducting Thienothiophene Copolymers: Design, Synthesis, Morphology, and Performance in Thin‐Film Organic Transistors

Abstract

Organic semiconductors are emerging as a viable alternative to amorphous silicon in a range of thin‐film transistor devices. With the possibility to formulate these p‐type materials as inks and subsequently print into patterned devices, organic‐based transistors offer significant commercial advantages for manufacture, with initial applications such as low performance displays and simple logic being envisaged. Previous limitations of both air stability and electrical performance are now being overcome with a range of both small molecule and polymer‐based solution‐processable materials, which achieve charge carrier mobilities in excess of 0.5 cm2 V−1 s−1, a benchmark value for amorphous silicon semiconductors. Polymer semiconductors based on thienothiophene copolymers have achieved amongst the highest charge carrier mobilities in solution‐processed transistor devices. In this Progress Report, we evaluate the advances and limitations of this class of polymer in transistor devices.

Influence of blend microstructure on bulk heterojunction organic photovoltaic performance

“…Initial studies have focussed upon blends of PCBM with poly(2,5-Bis(3-alkylThiophen-2-yl)Thieno[3,2-b]Thiophene) (pBTTT), which is an alternating co-polymer of thieno-[3,2-b]thiophene and 4,4-dialkyl 2,2-bithiophene repeat units. 36 The reduced sidechain density of pBTTT compared to P3HT facilitates the formation of highly ordered thin film structures, which are driven by interdigitation of the alkyl sidechains of adjacent polymer backbone.…”

Carrier Transport Enhancement in Conjugated Polymers through Interfacial Self-Assembly of Solution-State Aggregates

“…[5][6][7][8][9][10] A number of recent studies have demonstrated that molecular ordering along the polymer backbone and between chains is far more important to carrier transport in high molecular weight (Mw) polymer films than domain boundaries. [11][12][13][14][15][16] However, high Mw semi-flexible polymers are thought to be difficult to push into a highly molecularly ordered state due to entanglements and interactions which can inhibit molecular diffusion and challenge conformational transitions.…”

Ambient Electronics

“…32) Regarding low-molecular-weight organic semiconductors compatible with coating processes, a mobility of approximately 1 cm 2 V À1 s À1 has been reported for various materials, such as triisopropylsilylethynyl (TIPS) pentacene 33) and porphyrin- 34) and benzothienobenzothiophene (BTBT) 35) -based materials. Regarding polymers, a mobility of 0.5 cm 2 V À1 s À1 was achieved for thiophene-based polymers using crystalline materials, 36) and a mobility of 1 cm 2 V À1 s À1 was achieved for transistors fabricated by solution processing. 37) Many organic semiconductors, including not only p-type but also n-type organic semiconductors, have been reported because of the great diversity of organic compounds.…”

“…However, the degradation in the performance of p-type low-molecular-weight semiconductors due to atmospheric exposure has been reduced to a negligible level owing to recent progress in material technologies. [32][33][34][35][36][37][38][39][40][41]99,100) In the future, improved electrical characteristics, reliability, and stability will also be required for highly soluble semiconductors; the performance and stability of these organic semiconductors depend on the combination of insulating layers and electrodes used in the transistor structures. Namely, it is necessary to further enhance the compatibility among insulating layers, semiconductors, and electrodes by controlling their interfaces to realize higher stability.…”