Picosecond Capture of Photoexcited Electrons Improves Photovoltaic Conversion in MAPbI3:C70‐Doped Planar and Mesoporous Solar Cells |
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| Authors: | Saba Gharibzadeh Franco Valduga de Almeida Camargo Cristina Roldán‐Carmona Grégoire Clément Gschwend Jorge Pascual Ramón Tena‐Zaera Giulio Cerullo Giulia Grancini Mohammad Khaja Nazeeruddin |
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| Affiliation: | 1. Group for Molecular Engineering of Functional Materials, Ecole Polytechnique Fédérale Lausanne Valais Wallis, Sion, Switzerland;2. Department of Physics, Tarbiat Modares University, Tehran, Iran;3. Istituto di Fotonica e Nanotecnologie del CNR, Dipartimento di Fisica, Politecnico di Milano, Milano, Italy;4. LEPA, Ecole Polytechnique Fédérale Lausanne Valais Wallis, Sion, Switzerland;5. IK4‐CIDETEC, Parque Tecnológico de San Sebastián, Donostia‐San Sebastián, Spain;6. POLYMAT, University of the Basque Country UPV/EHU, Donostia‐San Sebastián, Spain |
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| Abstract: | In this work, solar cells based on methylammonium lead iodide (MAPbI3) doped in solution with C70 fullerene in a mesoporous as well as planar electron‐transporting layer (ETL)‐free architecture are realized, showcasing in the latter case a record efficiency of 15.7% and an improved open‐circuit voltage (VOC). Contrary to the bulk heterojunction previously reported, the C70 molecules do not phase segregate and they are rather finely dispersed in the perovskite film, possibly infiltrating at the grain boundaries, while assisting the growth of a highly uniform perovskite layer. By means of time‐resolved femtosecond‐to‐nanosecond optical spectroscopy, with an extended spectral coverage, it is observed that electrons photogenerated in the perovskite are transferred to C70 with a time constant of 20 ps. Despite being captured by C70, electrons are not deeply trapped and can potentially bounce back into the perovskite, as suggested by the high fill factor and enhanced VOC of the MAPbI3:C70 solar cells, especially in the case of the ETL‐free device configuration. |
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| Keywords: | C70:MAPbI3 interface electron transfer ETL free perovskite solar cells hybrid perovskite solar cells ultrafast dynamics |
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