Presentation Details
| Interface and bulk engineering for highly efficient and stable perovskite-based photovoltaics Fengjiu Yang, Ross Kenner, Xinwen Zhang, Joey Luther, Joseph Berry, Kai Zhu. National Laboratory of the Rockies, Golden, CO, USA |
Abstract
Organic-inorganic metal halide perovskites have attracted enormous attention due to their promise of high-performance and low-cost photovoltaic application. Their excellent performance in photovoltaic devices, high absorption coefficients, long charge carrier diffusion lengths, and high fractions of radiative recombination, tunable bandgap and solution process, have pushed single-junction and perovskite-Si 2T tandem to over 27% and 34.8%, respectively. However, significant research efforts on stability are still needed for commercialization of these photovoltaic technologies. Here, we will discuss new triple halide perovskite compositions with bandgaps of ~1.8 eV for all-perovskite tandem and 1.68 eV for perovskite-Si tandem, by combining bulk additives and surface treatments. With the function of the additive and surface treatment, the recombination losses of ~1.8 eV perovskite bulk and interfaces have been reduced, resulting in a longer carrier lifetime compared to control sample. As a result, the VOC of a single-junction ~1.8 eV device reached 1.36 V. We also found that the solvent drying step strongly affects the Voc value. By combining with the 1.8 eV perovskite top cell with a tinlead based narrow bandgap perovskite as a bottom cell, we produced an all-perovskite tandem solar cell with a certified efficiency of 27.5%. Similarly, the energetic alignment offset between 1.68 eV perovskite and carrier transport materials has decreased, resulting in a significant drop on recombination losses of perovskite film itself and interfaces. As a result, single-junction device achieved a VOC of over 1.29 V with an excellent operational stability, and >20% efficiency on a 16.8 cm2 module. This progress allows us to develop highly efficient perovskite-based tandems and towards commercialization.
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No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the author.