High‐Performance Phototransistor Based on a 2D Polybenzimidazole Polymer

作者：Anupam Prasoon, Preetam Dacha, Heng Zhang, Elif Ünsal, Mike Hambsch, Alexander Croy, Shuai Fu, Nguyen Ngan Nguyen, Kejun Liu, Haoyuan Qi, Sein Chung, Minyoung Jeong, Lei Gao, Ute Kaiser, Kilwon Cho, Hai I. Wang, Renhao Dong⧫, Gianaurelio Cuniberti, Mischa Bonn, Stefan C. B. Mannsfeld, Xinliang Feng · 发表于：Advanced Materials · 年份：2025 · DOI：10.1002/adma.202505810 · 被引用次数：7 · 研究领域：2D Materials and Applications、Graphene research and applications、Perovskite Materials and Applications

Abstract Photodetectors are fundamental components of modern optoelectronics, enabling the conversion of light into electrical signals. The development of high‐performance phototransistors necessitates materials with both high charge carrier mobility and robust photoresponse. However, achieving both in a single material poses challenges due to inherent trade‐offs. Herein, this study introduces a polybenzimidazole‐(1,3‐diazole)‐based 2D polymer (2DPBI), synthesized as few‐layer, crystalline films covering ≈28 cm 2 on the water surface at room temperature, with large crystalline domain sizes ranging from 110 to 140 µm 2 . The 2DPBI incorporates a π‐conjugated photoresponsive porphyrin motif through a 1,3‐diazole linkage, exhibiting enhanced π‐electron delocalization, a narrow direct band gap of ≈1.18 eV, a small reduced electron–hole effective mass ( m * = 0.171 m 0 ), and a very high resonant absorption coefficient of up to 10 6 cm −1 . Terahertz spectroscopy reveals excellent short‐range charge carrier mobility of ≈240 cm 2 V −1 s −1 . Temperature‐dependent photoconductivity measurements and theoretical calculations confirm a band‐like charge transport mechanism. Leveraging these features, 2DPBI‐based phototransistors demonstrate an on/off ratio exceeding 10 8 , photosensitivity of 1.08 × 10 7 , response time of 1.1 ms, and detectivity of 2.0 × 10 13 Jones, surpassing previously reported standalone few‐layer 2D materials and are on par with silicon photodetectors. The unique ...