Optimizing in-situ deposition of Perovskite nanocrystals for solar cell applications

Optimizing in-situ deposition of Perovskite nanocrystals for solar cell applications

Responsable : Fredrik Johansson
Contact : johansson@insp.upmc.fr
Tutelle : Sorbonne Université
Mots clés : Experimental et Stage M2
Gratification : Oui
Page des stages de(s) l'équipe(s) : Physico-chimie et dynamique des surfaces
Description du stage

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Defect tolerant nanocrystals (NCs) representing lead halide perovskite lattice (PeNCs) have recently been demonstrated to display remarkable photoluminescence (PL) efficiency [1]. Owing to their exceptional optical properties, PeNCs are promising candidates as absorber layer for highly efficient photovoltaic devices [2].

Solar cells are produced by stacking different functional layers, to absorb photons and to maximize the extraction and separation of positive and negative charges. In such stack, the resulting power conversion efficiency depends not only on the light harvesting material alone but also on the ability of the transport layers to extract charges effectively, this process being highly dependent on the quality of the interface between the different materials.

To stabilize the PeNC during synthesis, ligands, consisting of long carbon molecules, are used to stabilize the structure. However, when deposited as a film the long carbon molecules leads to poor conductivity both between the NCs, and to the transport layers. Making it necessary to exchange them for shorter molecules to improve conductivity, a process normally performed by dipping the PeNC film in ionic solutions. We now want to move to a in vacuum exchange technique.

The goal of the project is to develop a process for in vacuum ligand exchange using in-situ spray deposition, a technique currently used at the institute. The student will be responsible for the development of the ligand exchange scheme and the characterization of both the exchange- and film quality using techniques such as, transport measurement, X-ray diffraction (XRD), Rutherford backscattering spectrometry (RBS) and photoelectron spectroscopy.

As the research team is multinational, the applicant must speak English.

[1] Nano Lett. 2015, 15, 3692–3696 https://doi.org/10.1021/nl5048779

[2] Science, 2016, 354, 6308 DOI: 10.1126/science.aag270