Guan Zihao, Wei Zhiyuan, Liu Fang, Fu Lulu, Shan Naying, Zhao Yang, Huang Zhipeng, Humphrey Mark G, Zhang Chi
China-Australia Joint Research Center for Functional Molecular Materials, School of Chemical Science and Engineering, Tongji University, Shanghai 200092, China.
Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia.
ACS Appl Mater Interfaces. 2023 Oct 25. doi: 10.1021/acsami.3c12354.
Perovskite layer defects are a primary inhibiting factor for their optical nonlinearity, which restricts their use in nonlinear photonics devices. Nevertheless, due to the variety of defect types, the passivation and repair of these defects remain challenging. Herein, a novel bifunctional passivation strategy was proposed, and the porphyrin with a donor-π-acceptor structure was designed to bifunctionally repair perovskite defects by linking different types of functional groups via acetylenic π-conjugated linkage bridges on both sides, thus improving the nonlinear optical (NLO) absorption properties of porphyrin-perovskite hybrid materials. Research results indicate that the amino and carboxyl groups of porphyrins endow the ability to bifunctionally passivate charged defects via effective coordination interactions. The nonlinear absorption properties of all porphyrin-passivated MAPbI films were remarkably enhanced compared to that of the MAPbI film across multiple wavelengths and temporal domains. Particularly, the -passivated perovskite film () exhibited optimized strongest NLO performance, including reverse saturable absorption (RSA) under 800 nm femtosecond (fs) and 1064 nm nanosecond (ns) laser irradiations, as well as saturable absorption (SA) with 515 and 532 nm ns laser excitations. The value of the NLO absorption coefficient (β = 266.23 cm GW) is 1 order of magnitude higher than that of the pristine perovskite film (β = 12.93 cm GW), also outperforming other porphyrin-passivated perovskite films and some reported materials. The bifunctional passivation mechanism of porphyrin not only intensifies the perovskite's photoinduced ground-state dipole moment in the two-photon absorption (TPA) process and the free carrier absorption ability to deepen the RSA properties under 800 nm fs and 1064 nm ns lasers, respectively, but also enables the improvement of SA responses under 515 nm fs and 532 nm ns lasers by expediting the Pauli blocking effect of perovskite. Our study offers a viable paradigm, which aims at exploiting high-performance NLO perovskite materials across wide spectral regions and time scales.
钙钛矿层缺陷是其光学非线性的主要抑制因素，这限制了它们在非线性光子学器件中的应用。然而，由于缺陷类型的多样性，这些缺陷的钝化和修复仍然具有挑战性。在此，提出了一种新型双功能钝化策略，设计了具有供体-π-受体结构的卟啉，通过两侧的炔基π共轭连接桥连接不同类型的官能团，双功能修复钙钛矿缺陷，从而改善卟啉-钙钛矿杂化材料的非线性光学（NLO）吸收性能。研究结果表明，卟啉的氨基和羧基赋予了通过有效的配位相互作用双功能钝化带电缺陷的能力。与MAPbI薄膜相比，所有卟啉钝化的MAPbI薄膜在多个波长和时间域的非线性吸收性能都有显著提高。特别是，-钝化的钙钛矿薄膜（）表现出优化的最强NLO性能，包括在800 nm飞秒（fs）和1064 nm纳秒（ns）激光照射下的反饱和吸收（RSA），以及在515和532 nm ns激光激发下的饱和吸收（SA）。NLO吸收系数的值（β = 266.23 cm GW）比原始钙钛矿薄膜（β = 12.93 cm GW）高1个数量级，也优于其他卟啉钝化的钙钛矿薄膜和一些报道的材料。卟啉的双功能钝化机制不仅在双光子吸收（TPA）过程中增强了钙钛矿的光致基态偶极矩和自由载流子吸收能力，分别加深了800 nm fs和1064 nm ns激光下的RSA特性，还通过加速钙钛矿的泡利阻塞效应，提高了515 nm fs和532 nm ns激光下的SA响应。我们的研究提供了一个可行的范例，旨在开发跨宽光谱区域和时间尺度的高性能NLO钙钛矿材料。
