Chen Weijie

Publication date: 20 June 2018
Source:Joule, Volume 2, Issue 6
Author(s): Michael Saliba, Martin Stolterfoht, Christian M. Wolff, Dieter Neher, Antonio Abate
Michael Saliba is a Group Leader at the Adolphe Merkle Institute in Fribourg, Switzerland. His group studies novel materials focusing on perovskites for a sustainable energy future. Michael was a Marie Curie Fellow at EPFL. He obtained his PhD at Oxford University, an MSc with the Max Planck Institute for Solid State Research, and BSc degrees in mathematics and physics from Stuttgart University. Michael was awarded the Young Scientist Award of the German University Association, was named one of the World’s 35 Innovators Under 35 by the MIT Technology Review, and is a Member of the Global Young Academy. Martin Stolterfoht is a postdoctoral research fellow in the Soft Matter Physics group at the University of Potsdam, Germany. He completed his Master degree in Physics at the University of Graz and obtained his PhD at the University of Queensland Australia in 2016 before moving to Potsdam. His research is focused on improving device efficiency through a fundamental understanding of charge transport and recombination processes in perovskite and organic solar cells. Christian M. Wolff obtained an MSc in Physics from Ludwig-Maximilians- Universität München with a focus on spectroscopy on semiconductor nanomaterials for solar-to-fuel conversion with Prof. J. Feldmann. He joined Prof. Neher's group in 2015 investigating halide perovskites and loss mechanisms in single and multijunction solar cells. Dieter Neher is a full professor of Soft Matter Physics at the University of Potsdam, Germany. He received his Diploma in Physics and his PhD in Chemical Physics at the Johannes Gutenberg University in Mainz, Germany. He worked as a postdoctoral research fellow at the Optical Science Center in Tuscon and the CREOL in Orlando, US. His current research focuses on the understanding and improvement of the electrical and optoelectronic properties of organic conjugated materials, hybrid organic/inorganic systems and organometallic perovskite semiconductors, and the implementation of such materials into highly efficient devices. Antonio Abate is a group leader at the Helmholtz-Zentrum Berlin in Germany and Visiting Professor at Fuzhou University in China. His group is currently researching novel active materials and interfaces to make stable perovskite solar cells. Before his move to the Helmholtz, Antonio was leading the solar cell research at the Adolphe Merkle Institute in Switzerland. After his PhD in Politecnico di Milano in Italy, he was a Marie Skłodowska-Curie Fellow at École Polytechnique Fédérale de Lausanne and postdoctoral researcher at the University of Oxford.

Teaser

As perovskite solar cells approach maximum theoretical performances, stability becomes the next big challenge. However, ion migration, causing the infamous hysteresis effect, required measurement standards for efficiency. Analogously, it is now necessary to develop stability standards or else another “wild west” period, without comparable stability data, may ensue. Here, based on past findings, a tentative aging protocol and figures of merit are proposed. The protocol is then applied to inverted devices giving new insights into this relatively underexplored architecture.

Publication date: Available online 1 June 2018
Source:Joule
Author(s): Yuanzhi Jiang, Jin Yuan, Youxuan Ni, Jien Yang, Yao Wang, Tonggang Jiu, Mingjian Yuan, Jun Chen
Inorganic CsPbX3 perovskites have gained great attention owing to their excellent thermal stability and carrier transport properties. However, the power conversion efficiency (PCE) of solution-processed CsPbX3 perovskite solar cells is still far inferior to that of their hybrid analogues. Insufficient film thickness and undesirable phase transition are the two major obstacles limiting their device performance. Here, we show that by adopting a new precursor pair, cesium acetate (CsAc) and hydrogen lead trihalide (HPbX3), we were able to overcome the notorious solubility limitation for Cs precursors to fabricate high-quality CsPbX3 perovskite films with large film thickness (∼500 nm). We further introduced a judicious amount of phenylethylammonium iodide (PEAI) into the system to induce reduced-dimensional perovskite formation. Unprecedentedly, the resulting quasi-2D perovskites significantly suppressed undesirable phase transition and thus reduced the film's trap density. Following this approach, we reported a state-of-the-art PCE to date, 12.4%, for reduced-dimensional α-CsPbI3 perovskite photovoltaics with greatly improved performance longevity.

Graphical abstract

Teaser

CsAc and HPbX3 were adopted in CsPbX3 perovskite preparation, which led to high-quality CsPbX3 perovskite films with large film thickness (>500 nm). Taking advantage of this new precursor system, efficient CsPbIBr2 inorganic perovskite solar cells with record power conversion efficiency (PCE) of 8.54% were achieved. By introducing a judicious amount of PEAI into the new precursor pair, inorganic quasi-2D perovskites emerged and delivered a reproducible PCE of 12.4% for α-CsPbI3 with greatly improved stability.

Advanced Energy Materials, Volume 8, Issue 16, June 5, 2018.

Advanced Materials Interfaces, Volume 5, Issue 15, August 9, 2018.

Advanced Materials, EarlyView.

Semitransparent organic solar cells (STOSCs) based on ternary structure are rarely studied. Here, a high efficiency of 9.2% is achieved for the champion semitransparent ternary device with 20% average visible transmittance, which is among the highest power conversion efficiencies reported for STOSCs so far. This indicates that the ternary structure is a promising strategy to fabricate high‐performance STOSCs.

Abstract

Semitransparent organic solar cells (STOSCs) are ideal candidates for building‐integrated photovoltaics. Power conversion efficiency (PCE) is one of the most important parameters of STOSCs, which is typically limited by the intrinsic narrow absorption of thin active layer. Ternary structure is demonstrated as an efficient approach to broaden the light absorption and manipulate the morphology, thus leading to improved PCEs by introducing a third component into the binary system. However, STOSCs based on ternary systems are rarely studied. In this contribution, semitransparent ternary solar cells are fabricated using a wide‐bandgap (E _g = 2.10 eV) polymer donor, PBT1‐S, as the third component. It is found that the addition of a small amount of PBT1‐S to PTB7‐Th:PC₇₁BM blend has a negligible influence on its average visible transmittance (AVT) and color perception. A PCE of 9.2% is achieved for the champion ternary device with 20% AVT, which is one of the highest values for STOSCs. The results indicate that ternary structure is a promising approach for the fabrication of high‐performance STOSCs.

Advanced Energy Materials, Volume 8, Issue 22, August 6, 2018.

Advanced Materials, EarlyView.

Advanced Materials, EarlyView.