Pure crystal orientation and anisotropic charge transport in large-area hybrid perovskite films

• Published in: Nature communications Vol. 7; no. 1; p. 13407
• Main Authors: Cho, Namchul, Li, Feng, Turedi, Bekir, Sinatra, Lutfan, Sarmah, Smritakshi P., Parida, Manas R., Saidaminov, Makhsud I., Murali, Banavoth, Burlakov, Victor M., Goriely, Alain, Mohammed, Omar F., Wu, Tom, Bakr, Osman M.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 10.11.2016; Nature Publishing Group; Nature Portfolio
• Subjects: 639/301; 639/301/1005/1007; Engineering; Glass substrates; Humanities and Social Sciences; Materials science; Morphology; multidisciplinary; Science; Science (multidisciplinary); Single crystals; Solvents; Saudi Arabia
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms13407

Controlling crystal orientations and macroscopic morphology is vital to develop the electronic properties of hybrid perovskites. Here we show that a large-area, orientationally pure crystalline (OPC) methylammonium lead iodide (MAPbI 3 ) hybrid perovskite film can be fabricated using a thermal-gradient-assisted directional crystallization method that relies on the sharp liquid-to-solid transition of MAPbI 3 from ionic liquid solution. We find that the OPC films spontaneously form periodic microarrays that are distinguishable from general polycrystalline perovskite materials in terms of their crystal orientation, film morphology and electronic properties. X-ray diffraction patterns reveal that the film is strongly oriented in the (112) and (200) planes parallel to the substrate. This film is structurally confined by directional crystal growth, inducing intense anisotropy in charge transport. In addition, the low trap-state density (7.9 × 10 13  cm −3 ) leads to strong amplified stimulated emission. This ability to control crystal orientation and morphology could be widely adopted in optoelectronic devices. Lead halide perovskites are developed for a number of optoelectronic applications. Here, Cho et al . use a thermal gradient to achieve directional crystallization of methyl ammonium lead iodide films. The periodic microarrays exhibit anisotropic charge transport properties.