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Towards High Performance Perovskite-Based Tandem PV - 2D/3D Perovskite Heterostructures Enable High Open Circuit Voltage Wide-Bandgap Perovskite Solar Cells

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Date and time 17.05.2019 14:0015:00  
Place and room
Category Conferences - Seminars
Par Dr. Ulrich W. Paetzold
Institute of Microstructure Technology (IMT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany. Light Technology Institute (LTI), Engesserstrasse 13, Building 30.34, 76131 Karlsruhe, Germany

Abstract: The material class of mixed-halide organic-inorganic hybrid perovskites exhibits a tunable bandgap from 1.2 - 3.1 eV, simply by adjusting the ratio of the halide precursors. This property makes these materials excellent candidates for low-cost multi-junction photovoltaics (PV). In particular, wide-bandgap perovskites (WBP) with a bandgap ranging between EG ~ 1.7 - 1.8 eV are attractive top-cell materials to improve the power conversion efficiency (PCE) of single-junction crystalline silicon or thin-film CIGS solar cells in multi-junction PV. However, obtaining high open-circuit voltage (VOC), which is a mandatory requirement to achieve sufficient PCE, is still a key challenge for WBP solar cells. In this contribution, we report on wide-bandgap perovskite solar cells with a stable power output efficiency of up to 19.4% and a remarkable VOC of up to 1.31 V. The WBP solar cells in focus of this study employ a double-cation perovskite absorber layer based on FA and Cs in the composition FA0.83Cs0.17Pb(I0.6Br0.4)3 with a bandgap of 1.72 eV. By solution processing ammonium derivatives on top of the perovskite absorber layer, an interlayer is introduced between the bulk 3D perovskite absorber layer and the hole transport layer. As we will show by means of XRD studies, this interlayer is composed of 2D Ruddlesden-Popper perovskites in intermediate phases ofn = 2, resulting in a thin 2D/3D perovskite heterostructure at the hole extracting side of the solar cell. The devices with 2D/3D heterostructure achieve an enhancement in VOC of up to 80 mV, leading to a stable record VOC for WBPs (EG ~ 1.72 eV) of up to 1.31 eV. This very remarkable VOC reaches > 90% of the Shockley Queisser (SQ) limit and corresponds to one of the highest ratios of VOC-to-EG (0.76) reported for any perovskite solar cell with decent PCE. The devices with 2D/3D perovskite heterostructure show negligible hysteresis and demonstrate very high PCE of 19.8% with corresponding stable power output efficiency of 19.4% under continuous illumination of one sun irradiation intensity and maximum power point tracking. The stable performance and high reproducibility of the perovskite solar cells employing the 2D/3D perovskite heterostructure was proven further by providing data on the statistics of > 50 devices.

[1] S. Gharibzadeh, B. Abdollahi Nejand, M. Jakoby, T. Abzieher, D. Hauschild, S. Moghadamzadeh, J. A. Schwenzer, P. Brenner, R. Schmager, A. Haghighirad, L. Weinhardt, U. Lemmer, B. S. Richards, I. A. Howard, and U.W. Paetzold, Adv. Energy Mater. 1803699 (2019) [DOI: 10.1002/aenm.201803699].

Dr. Ulrich W. Paetzold leads the research group Advanced Optics and Materials for Next Generation Photovoltaics at Karlsruhe Institute of Technology. He was a doctoral student at Forschungszentrum Jülich and received his PhD in physics from RWTH Aachen University, then continued as a postdoc at imec in Leuven. In 2016, he was awarded an independent research group at Karlsruhe Institute of Technology. His research focusses on the interaction between light and structured matter for the purpose of engineering novel optical concepts and nanophotonic materials for solar energy harvesting. He is particularly interested in perovskite thin-film and perovskite-based multijunction PV.

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