Print Email Facebook Twitter Charge Carrier Dynamics in Co-evaporated MAPbI3with a Gradient in Composition Title Charge Carrier Dynamics in Co-evaporated MAPbI3with a Gradient in Composition Author Zhao, J. (TU Delft ChemE/Opto-electronic Materials) Li, Jia (Nanyang Technological University) Liu, X. (TU Delft ChemE/O&O groep) Bannenberg, L.J. (TU Delft RID/TS/Instrumenten groep) Bruno, Annalisa (Nanyang Technological University) Savenije, T.J. (TU Delft ChemE/Opto-electronic Materials) Date 2022 Abstract Co-evaporation of metal halide perovskites by thermal evaporation is an attractive method since it does not require harmful solvents and enables precise control of the film thickness. Furthermore, the ability to manipulate the Fermi level allows the formation of a graded homojunction, providing interesting opportunities to improve the charge carrier collection efficiency. However, little is known about how these properties affect the charge carrier dynamics. In this work, the structural and optoelectronic properties of co-evaporated MAPbI3 films varying in thickness (100, 400, and 750 nm) with a gradient in composition are analyzed. The X-ray diffraction patterns show that excess PbI2 is only present in the thick layers. From X-ray photoelectron spectroscopy depth analysis, the I/Pb atomic ratio indicates methylammonium iodide deficiencies that become more prominent with thicker films, resulting in differently n-doped regions across the thick MAPbI3 films. We suggest that due to these differently n-doped regimes, an internal electric field is formed. Side-selective time-resolved microwave photo conductivity measurements show an elongation of the charge carrier lifetimes on increasing thickness. These observations can be explained by the fact that excess carriers separate under the influence of the electric field, preventing rapid decay in the thick films. Subject charge carrier dynamicsco-evaporationmetal halide perovskitesphysical vapor depositiontime-resolved microwave conductivity To reference this document use: http://resolver.tudelft.nl/uuid:8e8320a4-495c-474a-9282-71e524ee28da DOI https://doi.org/10.1021/acsaem.2c00664 ISSN 2574-0962 Source ACS Applied Energy Materials, 5 (6), 7049-7055 Part of collection Institutional Repository Document type journal article Rights © 2022 J. Zhao, Jia Li, X. Liu, L.J. Bannenberg, Annalisa Bruno, T.J. Savenije Files PDF acsaem.2c00664.pdf 1.92 MB Close viewer /islandora/object/uuid:8e8320a4-495c-474a-9282-71e524ee28da/datastream/OBJ/view