shuhui

Advanced Energy Materials, July 2018.

Small, Volume 14, Issue 31, August 2, 2018.

Advanced Functional Materials, EarlyView.

Advanced Energy Materials, July 2018.

Advanced Energy Materials, July 2018.

Advanced Energy Materials, July 2018.

Advanced Energy Materials, July 2018.

Advanced Energy Materials, July 2018.

Advanced Energy Materials, July 2018.

Advanced Energy Materials, July 2018.

Advanced Energy Materials, July 2018.

Advanced Energy Materials, July 2018.

Advanced Energy Materials, July 2018.

Publication date: Available online 3 July 2018
Source:Joule
Author(s): Laura Caliò, Manuel Salado, Samrana Kazim, Shahzada Ahmad
The use of hydrophobic dopant is paramount for the success of organic semiconductors. Here we demonstrate the use of an N-heterocyclic hydrophobic ionic liquid, 1-butyl-3-methylpyridinium bis(trifluoromethylsulfonyl)imide (BMPyTFSI), to induce dual functionality: as p-type dopant and as additive for state-of-the-art Spiro-OMeTAD hole-transporting material (HTM). This ionic liquid doped HTM was then implemented for perovskite solar cell fabrication and delivered competitive results. The dopant has the ability to substitute state-of-the-art ultra-hygroscopic lithium salt (LiTFSI) and problematic 4-tert-butylpyridine (t-BP) additive. BMPyTFSI was found to increase the conductivity of Spiro-OMeTAD and its use as dopant in HTM reduces charge recombination, improves the film formation by reducing the pinholes on the HTM surface, and allows fabrication of efficient devices. Competitive air stability of solar cells in comparison with their state-of-the-art dopant was found, and these findings open up a broad range of organic semiconductors for hydrophobic ionic liquid-based doping.

Graphical abstract

Teaser

The use of perovskite as a semiconductor pigment has triggered its use for solar cell fabrication. On-par light-to-electricity conversion efficiency has been reported relative to mature thin-film photovoltaics technology. The use of hygroscopic lithium salts as a dopant in charge-selective layer compromises device long-term stability and induces intrinsic degradation. Here we report our findings on the use of an ultra-hydrophobic dopant, which works effectively and can rival the employment of state-of-the-art dopant.

Publication date: Available online 3 July 2018
Source:Joule
Author(s): Chen Sun, Ruoxi Xia, Hui Shi, Huifeng Yao, Xiang Liu, Jianhui Hou, Fei Huang, Hin-Lap Yip, Yong Cao
Semitransparent organic photovoltaics (ST-OPVs) have attracted extensive attention due to their potential for integration into the windows of buildings. Herein, we propose a dual-functional ST-OPV device that is not only highly efficient but also very effective for heat insulation. By introducing non-fullerene acceptor with enhanced near-infrared absorption and distributed Bragg reflectors for selectively enhancing the transmittance in visible wavelengths while keeping high reflectance for near-infrared light, the ST-OPVs generate over 6% power conversion efficiency with high visible light transmission of over 25% and outstanding infrared radiation rejection rate of over 80%. Our results show that with proper design of ST-OPVs, they can be used not only for generating power from sunlight but also for solar shading and heat insulation, which opens up a new application of OPVs for both energy harvesting and saving.

Graphical abstract

Teaser

A dual-functional semitransparent organic photovoltaic cell that integrates both power-generation and heat-insulation functions is demonstrated. By introducing non-fullerene acceptor with enhanced near-infrared absorption and distributed Bragg reflectors for selectively keeping high reflectance for near-infrared light, the solar cell generates over 6% power conversion efficiency with high visible light transmission of over 25% in addition to an excellent infrared radiation rejection rate of over 80%.

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.

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 7 May 2018
Source:Joule
Author(s): Hui Bian, Dongliang Bai, Zhiwen Jin, Kang Wang, Lei Liang, Haoran Wang, Jingru Zhang, Qian Wang, Shengzhong (Frank) Liu
All-inorganic perovskite shows great potential for photovoltaic applications due to its excellent solar cell performance and atmospheric stability. Here, a CsPbI2+x Br1−x perovskite solar cell with a graded bandgap is explored using CsPbBrI2 and CsPbI3 quantum dots as component cells. Four strategies were pursued to boost the device performance. First, CsPbI2Br film was fabricated as the main absorber, with the component cell showing remarkable power conversion efficiency (PCE) as high as 13.45%. Second, by Mn²⁺ substitution, SCN⁻ capping, and [(NH2)2CH]⁺ treatment, stable and high-mobility CsPbI3 quantum dot (QD) film was attained. Third, a halide-ion-profiled heterojunction was designed at the CsPbBrI2/CsPbI3 QD interface to achieve proper band-edge bending as graded bandgap for improved carrier collection. Finally, the CsPbI3 QD layer was optimized in the graded bandgap structure to achieve maximum overall light harvesting. As a result, the device achieved a PCE of 14.45%. This is the highest efficiency ever reported for inorganic perovskite solar cells.

Graphical abstract

Teaser

Here, a high-performance graded bandgap structure-based solar cell was designed and demonstrated, comprising a CsPbI2Br bottom cell and a CsPbI3 QD top cell. Several optimizations were conducted to boost the device performance. As a result, the extended photoresponse, high carrier mobility, and well-matched energy levels afford a record power conversion efficiency of 14.45%, coupled with a high J SC of 15.25 mA/cm². The result shows that optical and energy-band manipulation is an effective approach for improving the performance of inorganic perovskite solar cells.