| 1. |
- Garcia Fernandez, Alberto, et al.
(författare)
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Interface Energy Alignment between Lead Halide Perovskite Single Crystals and TIPS-Pentacene
- 2023
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 62:38, s. 15412-15420
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Tidskriftsartikel (refereegranskat)abstract
- At present, there is a huge development in optoelectronic applications using lead halide perovskites. Considering that device performance is largely governed by the transport of charges across interfaces and, therefore, the interfacial electronic structure, fundamental investigations of perovskite interfaces are highly necessary. In this study, we use high-resolution soft X-ray photoelectron spectroscopy based on synchrotron radiation to explore the interfacial energetics for the molecular layer of TIPS-pentacene and lead halide perovskite single crystals. We perform ultrahigh vacuum studies on multiple thicknesses of an in situ formed interface of TIPS-pentacene with four different in situ cleaved perovskite single crystals (MAPbI3, MAPbBr3, FAPbBr3, and CsxFA1-xPbBryI3-y). Our findings reveal a substantial shift of the TIPS-pentacene energy levels toward higher binding energies with increasing thickness, while the perovskite energy levels remain largely unaffected regardless of their composition. These shifts can be interpreted as band bending in the TIPS-pentacene, and such effects should be considered when assessing the energy alignment at perovskite/organic transport material interfaces. Furthermore, we were able to follow a reorganization on the MAPbI3 surface with the transformation of the surface C 1s into bulk C 1s.
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| 2. |
- Svanström, Sebastian, et al.
(författare)
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Direct Measurements of Interfacial Photovoltage and Band Alignment in Perovskite Solar Cells Using Hard X-ray Photoelectron Spectroscopy
- 2023
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 15:9, s. 12485-12494
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Tidskriftsartikel (refereegranskat)abstract
- A heterojunction is the key junction for charge extraction in many thin film solar cell technologies. However, the structure and band alignment of the heterojunction in the operating device are often difficult to predict from calculations and, due to the complexity and narrow thickness of the interface, are difficult to measure directly. In this study, we demonstrate a technique for direct measurement of the band alignment and interfacial electric field variations of a fully functional lead halide perovskite solar cell structure under operating conditions using hard X-ray photoelectron spectroscopy (HAXPES). We describe the design considerations required in both the solar cell devices and the measurement setup and show results for the perovskite, hole transport, and gold layers at the back contact of the solar cell. For the investigated design, the HAXPES measurements suggest that 70% of the photovoltage was generated at this back contact, distributed rather equally between the hole transport material/gold interface and the perovskite/hole transport material interface. In addition, we were also able to reconstruct the band alignment at the back contact at equilibrium in the dark and at open circuit under illumination.
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