Direct Probing of Gap States and Their Passivation in Halide Perovskites by High-Sensitivity, Variable Energy Ultraviolet Photoelectron Spectroscopy
| Autor: | David Cahen, Alberto Lomuscio, Arava Zohar, Hisao Ishii, Richard H. Friend, Mojtaba Abdi-Jalebi, Kohei Shimizu, Igal Levine, Gary Hodes, Carolin Rehermann, Antoine Kahn, Fengshuo Zu, Baodan Zhao, Susanne Siebentritt, Michael Kulbak, Norbert Koch |
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| Rok vydání: | 2021 |
| Předmět: |
Materials science
Passivation business.industry Halide 02 engineering and technology Standard methods 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences halide perovskites utilizing optical excitation 0104 chemical sciences Surfaces Coatings and Films Electronic Optical and Magnetic Materials General Energy Low density Optoelectronics Physical and Theoretical Chemistry 0210 nano-technology business Sensitivity (electronics) Energy (signal processing) Excitation Ultraviolet photoelectron spectroscopy |
| Zdroj: | The Journal of Physical Chemistry C. 125:5217-5225 |
| ISSN: | 1932-7455 1932-7447 |
| Popis: | Direct detection of intrinsic defects in halide perovskites HaPs by standard methods utilizing optical excitation is quite challenging, due to the low density of defects in most samples of this family of materials lt; 10 15 cm 3 in polycrystalline thin films and lt; 10 11 cm 3 in single crystals, except melt grown ones . While several electrical methods can detect defect densities lt;10 15 cm 3, such as deep level transient spectroscopy DLTS or thermally stimulated current TSC , they require preparation of ohmic and or rectifying electrical contacts to the sample, which not only poses a challenge by itself in the case of HaPs but also may create defects at the contact HaP interface and introduce extrinsic defects into the HaP. Here, we show that low energy photoelectron spectroscopy measurements can be used to obtain directly the energy position of gap states in Br based wide bandgap E g gt; 2 eV HaPs. By measuring HaP layers on both hole and electron contact layers, as well as single crystals without contacts, we conclude that the observed deep defects are intrinsic to the Br based HaP, and we propose a passivation route via the incorporation of a 2D forming ligand into the precursor solution |
| Databáze: | OpenAIRE |
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