Solution Processing and Self-Organization of PbS Quantum Dots Passivated with Formamidinium Lead Iodide (FAPbI3)

Samaneh Aynehband; Maryam Mohammadi; Kerstin Thorwarth; Roland Hany; Frank Alain Nüesch; Marta D Rossell; Robin Pauer; Jean-Michel Nunzi; Abdolreza Simchi

doi:10.1021/acsomega.0c02319

Solution Processing and Self-Organization of PbS Quantum Dots Passivated with Formamidinium Lead Iodide (FAPbI₃)

ACS Omega. 2020 Jun 19;5(25):15746-15754. doi: 10.1021/acsomega.0c02319. eCollection 2020 Jun 30.

Authors

Samaneh Aynehband^{1

2

3}, Maryam Mohammadi¹, Kerstin Thorwarth⁴, Roland Hany², Frank Alain Nüesch^{2

5}, Marta D Rossell⁶, Robin Pauer⁶, Jean-Michel Nunzi³, Abdolreza Simchi^{1

7}

Affiliations

¹ Department of Materials Science and Engineering, Sharif University of Technology, 14588 Tehran, Iran.
² Laboratory for Functional Polymers, Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland.
³ Department of Chemistry, Department of Physics, Engineering Physics and Astronomy, Queens University, Kingston, Ontario K7L 3N6, Canada.
⁴ Surface Science and Coating Technologies, Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland.
⁵ Institute of Materials Science and Engineering, EPFL, Ecole Polytechnique Fédérale de Lausanne, Station 12, 1015 Lausanne, Switzerland.
⁶ Electron Microscopy Center, Empa, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, 8600 Dübendorf, Switzerland.
⁷ Institute for Nanoscience and Nanotechnology, Sharif University of Technology, 14588 Tehran, Iran.

Abstract

Solution-processed lead sulfide quantum dots (PbS QDs) are very attractive as NIR-active semiconductors for the fabrication of cost-efficient optoelectronic devices. To control the thin film carrier transport, as well as stability, surface passivation is of crucial importance. Here, we present the successful surface passivation of PbS QDs by the formamidinium lead iodide (FAPbI₃) ligand. An effective procedure for the fabrication of FAPbI₃-passivated PbS QDs through a binary-phase ligand exchange protocol in hexane and n-methylformamide is demonstrated. It is shown that this solution-processed ligand exchange drastically changes the photoluminescence intensity, exciton recombination dynamics, and carrier lifetime of the nanocrystals. The solution casting of the ligand-exchanged nanocrystals into thin films results in the periodic ordering of QDs in a square superlattice with close contacts. Planar graphene/QD photodetectors fabricated with PbS QDs passivated with FAPbI₃ show substantially increased thermal stability as compared to similar devices using PbS QDs passivated with commonly used methylammonium lead iodide.