Water-surface Drag Coating: A New Route Toward High-quality Conjugated Small-molecule Thin Films with Enhanced Charge Transport Properties
水面拖塗法大幅提升有機共軛小分子半導體薄膜電荷輸運性能
W. Deng, Y. Xiao, B. Lu, L. Zhang, Y. Xia, C. Zhu, X. Zhang, J. Guo, X. Zhang, and J. Jie*
2021/06/01
Electronic properties of organic semiconductor (OSC) thin films are largely determined by their morphologies and crystallinities. However, solution‐processed conjugated small‐molecule OSC thin films usually exhibit abundant grain boundaries and impure grain orientations because of complex fluid dynamics during solution coating. Here, a novel methodology, water‐surface drag coating, is demonstrated to fabricate high‐quality OSC thin films with greatly enhanced charge transport properties. This method utilizes the water surface to alter the evaporation dynamics of solution to enlarge the grain size, and a unique drag‐coating process to achieve the unidirectional growth of organic crystals. Using 2,8‐difluoro‐5,11‐bis(triethylsilylethynyl)anthradithiophene (Dif‐TES‐ADT) as an example, thin films with millimeter‐sized single‐crystal domains and pure crystallographic orientations are achieved, revealing a significant enhancement (4.7 times) of carrier mobility. More importantly, the resulting film can be directly transferred onto any desired flexible substrates, and flexible transistors based on the Dif‐TES‐ADT thin films show a mobility as high as 16.1 cm2 V−1 s−1, which represents the highest mobility value for the flexible transistors reported thus far. The method is general for the growth of various high‐quality OSC thin films, thus opening up opportunities for high‐performance organic flexible electronics.
有機場效應電晶體遷移率很大程度上取決於半導體層形貌和結晶度，但目前廣泛使用的Meniscus-guided coating技術中所涉及的流體動力學行為，如恒接觸角蒸發模式和流型不穩定性等，致使獲得的有機小分子薄膜中存在大量晶界以及結晶取向混亂的晶粒，導致電晶體遷移率降低。為此，蘇州大學功能納米與軟物質研究院揭建勝課題組報導了一種新型水面拖塗技術改變了傳統溶液塗布中的流體動力學行為，從而減少了薄膜的晶界、提高了晶粒取向的一致性，實現了遷移率超過10 cm2 V-1 s-1的柔性電晶體。該方法以水面作為生長基底，利用水面上有機溶液的Marangoni效應，將溶劑蒸發動力學過程由恒接觸角模式變為恒接觸線模式。增強了有機分子的橫向二維生長，從而提高了薄膜晶域的尺寸減少了晶界。採用拖塗方式引導晶體連續生長，避免了直接將外力施加在溶液上，使得三相接觸線保持不動，穩固了流體內部傳質過程，確保了薄膜中晶粒取向的一致。通過水面拖塗法制得的Dif-TES-ADT薄膜遷移率相比傳統溶液塗布技術提高了4.7倍，達到了該材料目前報導的最高遷移率之一。本研究使用TPS 44A1光束線。
研究動態
