Origin of vertical orientation in two-dimensional metal halide perovskites and its effect on photovoltaic performance

• Published in: Nature communications Vol. 9; no. 1; pp. 1336 - 7
• Main Authors: Chen, Alexander Z., Shiu, Michelle, Ma, Jennifer H., Alpert, Matthew R., Zhang, Depei, Foley, Benjamin J., Smilgies, Detlef-M., Lee, Seung-Hun, Choi, Joshua J.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 06.04.2018; Nature Publishing Group; Nature Portfolio
• Subjects: 639/301/299/946; 639/925/357/1018; Charge transport; Crystals; Dimensional stability; Humanities and Social Sciences; MATERIALS SCIENCE; Metal halides; Metal oxides; Metals; Methods; multidisciplinary; Optoelectronic devices; Oxides; Perovskites; Photovoltaics; Polymers; Science; Science (multidisciplinary); Substrates; Thin films; Vertical orientation
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-018-03757-0

Thin films based on two-dimensional metal halide perovskites have achieved exceptional performance and stability in numerous optoelectronic device applications. Simple solution processing of the 2D perovskite provides opportunities for manufacturing devices at drastically lower cost compared to current commercial technologies. A key to high device performance is to align the 2D perovskite layers, during the solution processing, vertical to the electrodes to achieve efficient charge transport. However, it is yet to be understood how the counter-intuitive vertical orientations of 2D perovskite layers on substrates can be obtained. Here we report a formation mechanism of such vertically orientated 2D perovskite in which the nucleation and growth arise from the liquid–air interface. As a consequence, choice of substrates can be liberal from polymers to metal oxides depending on targeted application. We also demonstrate control over the degree of preferential orientation of the 2D perovskite layers and its drastic impact on device performance. It is desirable to align the two-dimensional perovskite layers vertical to the electrodes to maximize device performance but the formation mechanism is unclear. Here Chen et al. reveal that the film formation starts at the liquid-air interface and is thus independent of the choice of substrates.