Ultra-smooth organic-inorganic perovskite thin-film formation and crystallization for Efficient Planar Heterojunction Solar Cells

Wei Zhang^a, Antonio Abate^j, Aditya Sadhanala^k, Shuhua Yao^l, Yulin Chen^m, Richard Friendⁿ, Lara Estroff^o, Ulrich Wiesner^p, Henry J. Snaith^q, Michael Saliba^b, David Moore^c, Sandeep Pathak^d, Maximilian Hörantner^e, Thomas Stergiopoulos^f, Samuel Stranks^g, Giles Eperon^h, Jack Alexander-Webberⁱ

^aUniversity of Oxford, Clarendon Laboratory, Parks rd, Oxford, 0, United Kingdom

^bUniversity of Oxford, Clarendon Laboratory, Parks rd, Oxford, 0, United Kingdom

^cCornell University, Department of Materials Science and Engineering, Ithaca, NY 14853, USA, Ithaca, United States

^dUniversity of Oxford, Clarendon Laboratory, Parks rd, Oxford, 0, United Kingdom

^eUniversity of Oxford, Clarendon Laboratory, Parks rd, Oxford, 0, United Kingdom

^fUniversity of Oxford, Clarendon Laboratory, Parks rd, Oxford, 0, United Kingdom

^gUniversity of Oxford, Clarendon Laboratory, Parks rd, Oxford, 0, United Kingdom

^hUniversity of Oxford, Clarendon Laboratory, Parks rd, Oxford, 0, United Kingdom

ⁱUniversity of Oxford, Clarendon Laboratory, Parks rd, Oxford, 0, United Kingdom

^jUniversity of Oxford, Clarendon Laboratory, Parks rd, Oxford, 0, United Kingdom

^kCavendish Laboratory, University of Cambridge - UK, JJ Thomson Avenue, 9, Cambridge, United Kingdom

^lNational Laboratory of Solid State Microstructures and Department of Materials Science and Engineering, Nanjing University, Nanjing 210093, China

^mUniversity of Oxford, Clarendon Laboratory, Parks rd, Oxford, 0, United Kingdom

ⁿCavendish Laboratory, University of Cambridge - UK, JJ Thomson Avenue, 9, Cambridge, United Kingdom

^oCornell University, Department of Materials Science and Engineering, Ithaca, NY 14853, USA, Ithaca, United States

^pCornell University, Department of Materials Science and Engineering, Ithaca, NY 14853, USA, Ithaca, United States

^qUniversity of Oxford, Clarendon Laboratory, Parks rd, Oxford, 0, United Kingdom

International Conference on Hybrid and Organic Photovoltaics
Proceedings of International Conference on Hybrid and Organic Photovoltaics 2015 (HOPV15)

Roma, Italy, 2015 May 11th - 13th

Organizer: Filippo De Angelis

Oral, Wei Zhang, presentation 208
Publication date: 5th February 2015

To date, there have been a plethora of reports on different means to fabricate organic-inorganic metal halide perovskitethin films, but the inorganic starting materials have been limited to halide based anions. In this work, we employ several lead salts, lead chloride (PbCl₂), lead iodide (PbI₂), and lead acetate (PbAc₂) in conjunction with a 3 molar excess of methylammonium iodide (CH₃NH₃I). All material processing routes lead to the formation of CH₃NH₃PbI₃with undetectable amounts of the “spectator” anion (Cl or Ac) but with considerably different thin film properties. In the latter case, PbAc₂, the only halide source in the final perovskite film is from CH₃NH₃I, which helps to identify more clearly what role the spectator ion (Cl or Ac) plays during perovskite film formation. Our findings reveal that the anion has a substantial effect on the perovskite crystal growth kinetics and film morphology. By simple one-step solution coating using PbAc₂ as lead source, we obtain a compact perovskite film with full-coverage on the substrate. Surprisingly, the smoothness of the films surpasses that of vapor-deposited films. Additionally, the processing time is greatly reduced to a few minutes for the PbAc₂ route due to the more rapid loss of excess organic material and ensuing faster crystal growth. By optimizing device fabrication conditions, we achieve a power conversion efficiency of 15.2% in a planar heterojunction architecture through the PbAc₂ route, measured under one sun illumination, which is a significant improvement upon similar solar cells fabricated from either PbCl₂ or PbI₂ routes. Our work paves the way to tune the crystal growth kinetics by simple chemistry.

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International Conference on Hybrid and Organic Photovoltaics

International Conference on Hybrid and Organic Photovoltaics (HOPV) is celebrated yearly in May. The main topics are the development, function and modeling of materials and devices for hybrid and organic solar cells. The field is now dominated by perovskite solar cells but also other hybrid technologies, as organic solar cells, quantum dot solar cells, and dye-sensitized solar cells and their integration into devices for photoelectrochemical solar fuel production.

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International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and Optoelectronics

The International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and Optoelectronics (NIPHO) is the best place to hear the latest developments in perovskite solar cells as well as on recent advances in the fields of perovskite light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.