Lai Zhengxun, Dong Ruoting, Zhu Qi, Meng You, Wang Fei, Li Fangzhou, Bu Xiuming, Kang Xiaolin, Zhang Heng, Quan Quan, Wang Wei, Wang Feng, Yip SenPo, Ho Johnny C
Department of Materials Science and Engineering, City University of Hong Kong, Kowloon 999077, Hong Kong SAR, P. R. China.
State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 3888 Dongnanhu Road, Changchun 130021, P. R. China.
ACS Appl Mater Interfaces. 2020 Sep 2;12(35):39567-39577. doi: 10.1021/acsami.0c09651. Epub 2020 Aug 24.
Quasi-2D halide perovskites, especially the Ruddlesden-Popper perovskites (RPPs), have attracted great attention because of their promising properties for optoelectronics; however, there are still serious drawbacks, such as inefficient charge transport, poor stability, and unsatisfactory mechanical flexibility, restricting further utilization in advanced technologies. Herein, high-quality quasi-2D halide perovskite thin films are successfully synthesized with the introduction of the unique bication ethylenediammonium (EDA) via a one-step spin-coating method. This bication EDA, with short alkyl chain length, can not only substitute the typically bulky and weakly van der Waals-interacted organic bilayer spacer cations forming the novel Dion-Jacobson phase to enhance the mechanical flexibility of the quasi-2D perovskite (e.g., EDA(MA)PbI; MA = CHNH) but also serve as a normal cation to achieve the more intact films (e.g., (BA)(MA)(EDA)PbI). When fabricated into photodetectors, these optimized EDA-based perovskites deliver an excellent responsivity of 125 mA/W and a fast response time down to 380 μs under 532 nm irradiation. More importantly, the device with the Dion-Jacobson phase perovskite can be bent down to a radius of 2 mm and processed with 10,000 cycles of the bending test without any noticeable performance degradation because of its superior structure to RPPs. Besides, these films do not exhibit any material deterioration after ambient storage for 30 days. All these performance parameters are already comparable or even better than those of the state-of-the-art RPPs recently reported. This work provides valuable design guidelines of the quasi-2D perovskites to obtain high-performance flexible photodetectors for next-generation optoelectronics.
准二维卤化物钙钛矿，尤其是拉德勒斯登-波珀钙钛矿（RPPs），因其在光电子学方面的优异性能而备受关注；然而，仍然存在严重的缺点，如电荷传输效率低、稳定性差和机械柔韧性不理想，限制了其在先进技术中的进一步应用。在此，通过一步旋涂法成功合成了高质量的准二维卤化物钙钛矿薄膜，其中引入了独特的双阳离子乙二胺（EDA）。这种双阳离子EDA具有短烷基链长度，不仅可以取代通常体积大且范德华相互作用弱的有机双层间隔阳离子，形成新型的狄翁-雅各布森相，以增强准二维钙钛矿的机械柔韧性（例如，EDA(MA)PbI；MA = CHNH），还可以作为普通阳离子来获得更完整的薄膜（例如，(BA)(MA)(EDA)PbI）。当制成光电探测器时，这些优化的基于EDA的钙钛矿在532 nm光照下具有125 mA/W的优异响应度和低至380 μs的快速响应时间。更重要的是，具有狄翁-雅各布森相钙钛矿的器件可以弯曲到2 mm的半径，并经过10000次弯曲测试循环，由于其结构优于RPPs，性能没有明显下降。此外，这些薄膜在环境储存30天后没有出现任何材料劣化。所有这些性能参数已经与最近报道的最先进的RPPs相当甚至更好。这项工作为准二维钙钛矿提供了有价值的设计指导，以获得用于下一代光电子学的高性能柔性光电探测器。
