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Molecular Materials for Energy Conversion and Storage Technologies

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A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Electrochemistry".

Deadline for manuscript submissions: closed (31 December 2021) | Viewed by 13385

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Special Issue Editors

Dr. Sergei Manzhos

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Guest Editor

School of Materials and Chemical Technology, Tokyo Institute of Technology, Ookayama 2-12-1, Meguro-ku, Tokyo 152-8552, Japan
Interests: metal ion batteries; solar cells; computational spectroscopy; machine learning
Special Issues, Collections and Topics in MDPI journals

Prof. Dr. Il Jeon

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1. Department of Mechanical Engineering, The University of Tokyo, Tokyo, Japan
2. KU-KIST Green School Graduate School of Energy and Environment, Korea University, Seoul, Korea
Interests: carbon nanotube; fullerene; graphene; carbon electrodes; perovskite solar cells; organic solar cells; silicon solar cells; flexible devices; stretchable devices

Special Issue Information

Dear Colleagues,

Emerging energy conversion and storage technologies use molecular materials to achieve a high level of performance, for example, electron/hole transport materials in perovskite-based solar cells (PSC), hosts or emitters in light emitting diodes (LED), or active electrode materials in lithium and sodium ion batteries. It is not a stretch to say that progress in molecular material development is a key determinant in the eventual success of these technologies.

The development, characterization, and computational modelling of molecular materials for these diverse applications often rely on similar methods, tools, and ideas for rational design of characteristics such as redox potential, charge transport properties, and optical properties. Recent developments have also demonstrated that molecular materials can be versatile in that the same molecule or molecular design can be successfully used in several of these technologies.

This Special Issue aims to bring together work on molecular design by experimental and computational means for application in energy conversion and storage to highlight common design themes among the technologies and to facilitate the cross-fertilization of ideas needed for the development of high performance molecular materials.

Dr. Sergei Manzhos
Prof. Il Jeon
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

perovskite solar cells
organic solar cells
light emitting diodes
electron transport materials
hole transport materials
organic batteries
redox flow batteries

Published Papers (4 papers)

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Research

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12 pages, 3552 KiB

Open AccessArticle

Module-Designed Carbon-Coated Separators for High-Loading, High-Sulfur-Utilization Cathodes in Lithium–Sulfur Batteries

by Yi-Chen Huang, Yin-Ju Yen, Yu-Hsun Tseng and Sheng-Heng Chung

Molecules 2022, 27(1), 228; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules27010228 - 30 Dec 2021

Cited by 16 | Viewed by 1989

Abstract

Lithium–sulfur batteries have great potential as next-generation energy-storage devices because of their high theoretical charge-storage capacity and the low cost of the sulfur cathode. To accelerate the development of lithium–sulfur technology, it is necessary to address the intrinsic material and extrinsic technological challenges brought about by the insulating active solid-state materials and the soluble active liquid-state materials. Herein, we report a systematic investigation of module-designed carbon-coated separators, where the carbon coating layer on the polypropylene membrane decreases the irreversible loss of dissolved polysulfides and increases the reaction kinetics of the high-loading sulfur cathode. Eight different conductive carbon coatings were considered to investigate how the materials’ characteristics contribute to the lithium–sulfur cell’s cathode performance. The cell with a nonporous-carbon-coated separator delivered an optimized peak capacity of 1112 mA∙h g⁻¹ at a cycling rate of C/10 and retained a high reversible capacity of 710 mA∙h g⁻¹ after 200 cycles under lean-electrolyte conditions. Moreover, we demonstrate the practical high specific capacity of the cathode and its commercial potential, achieving high sulfur loading and content of 4.0 mg cm⁻² and 70 wt%, respectively, and attaining high areal and gravimetric capacities of 4.45 mA∙h cm⁻² and 778 mA∙h g⁻¹, respectively. Full article

(This article belongs to the Special Issue Molecular Materials for Energy Conversion and Storage Technologies)

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11 pages, 2157 KiB

Open AccessCommunication

Multi-Walled Carbon Nanotube-Assisted Encapsulation Approach for Stable Perovskite Solar Cells

by Jin-Myung Choi, Hiroki Suko, Kyusun Kim, Jiye Han, Sangsu Lee, Yutaka Matsuo, Shigeo Maruyama, Il Jeon and Hirofumi Daiguji

Molecules 2021, 26(16), 5060; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26165060 - 20 Aug 2021

Cited by 8 | Viewed by 2840

Abstract

Perovskite solar cells (PSCs) are regarded as the next-generation thin-film energy harvester, owing to their high performance. However, there is a lack of studies on their encapsulation technology, which is critical for resolving their shortcomings, such as their degradation by oxygen and moisture. It is determined that the moisture intrusion and the heat trapped within the encapsulating cover glass of PSCs influenced the operating stability of the devices. Therefore, we improved the moisture and oxygen barrier ability and heat releasing capability in the passivation of PSCs by adding multi-walled carbon nanotubes to the epoxy resin used for encapsulation. The 0.5 wt% of carbon nanotube-added resin-based encapsulated PSCs exhibited a more stable operation with a ca. 30% efficiency decrease compared to the ca. 63% decrease in the reference devices over one week under continuous operation. Specifically, the short-circuit current density and the fill factor, which are affected by moisture and oxygen-driven degradation, as well as the open-circuit voltage, which is affected by thermal damage, were higher for the multi-walled carbon nanotube-added encapsulated devices than the control devices, after the stability test. Full article

(This article belongs to the Special Issue Molecular Materials for Energy Conversion and Storage Technologies)

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Review

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19 pages, 2872 KiB

Open AccessReview

Aggregate-State Effects in the Atomistic Modeling of Organic Materials for Electrochemical Energy Conversion and Storage Devices: A Perspective

by Sergei Manzhos

Molecules 2020, 25(9), 2233; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules25092233 - 09 May 2020

Cited by 4 | Viewed by 2568

Abstract

Development of new functional materials for novel energy conversion and storage technologies is often assisted by ab initio modeling. Specifically, for organic materials, such as electron and hole transport materials for perovskite solar cells, LED (light emitting diodes) emitters for organic LEDs (OLEDs), and active electrode materials for organic batteries, such modeling is often done at the molecular level. Modeling of aggregate-state effects is onerous, as packing may not be known or large simulation cells may be required for amorphous materials. Yet aggregate-state effects are essential to estimate charge transport rates, and they may also have substantial effects on redox potentials (voltages) and optical properties. This paper summarizes recent studies by the author’s group of aggregation effects on the electronic properties of organic materials used in optoelectronic devices and in organic batteries. We show that in some cases it is possible to understand the mechanism and predict specific performance characteristics based on simple molecular models, while in other cases the inclusion of effects of aggregation is essential. For example, it is possible to understand the mechanism and predict the overall shape of the voltage-capacity curve for insertion-type organic battery materials, but not the absolute voltage. On the other hand, oligomeric models of p-type organic electrode materials can allow for relatively reliable estimates of voltages. Inclusion of aggregate state modeling is critically important for estimating charge transport rates in materials and interfaces used in optoelectronic devices or when intermolecular charge transfer bands are important. We highlight the use of the semi-empirical DFTB (density functional tight binding) method to simplify such calculations. Full article

(This article belongs to the Special Issue Molecular Materials for Energy Conversion and Storage Technologies)

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12 pages, 1412 KiB

Open AccessFeature PaperReview

Computational Studies of Molecular Materials for Unconventional Energy Conversion: The Challenge of Light Emission by Thermally Activated Delayed Fluorescence

by Javier Sanz-Rodrigo, Yoann Olivier and Juan-Carlos Sancho-García

Molecules 2020, 25(4), 1006; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules25041006 - 24 Feb 2020

Cited by 17 | Viewed by 4514

Abstract

In this paper we describe the mechanism of light emission through thermally activated delayed fluorescence (TADF)—a process able to ideally achieve 100% quantum efficiencies upon fully harvesting the energy of triplet excitons, and thus minimizing the energy loss of common (i.e., fluorescence and phosphorescence) luminescence processes. If successful, this technology could be exploited for the manufacture of more efficient organic light-emitting diodes (OLEDs) made of only light elements for multiple daily applications, thus contributing to the rise of a sustainable electronic industry and energy savings worldwide. Computational and theoretical studies have fostered the design of these all-organic molecular emitters by disclosing helpful structure–property relationships and/or analyzing the physical origin of this mechanism. However, as the field advances further, some limitations have also appeared, particularly affecting TD-DFT calculations, which have prompted the use of a variety of methods at the molecular scale in recent years. Herein we try to provide a guide for beginners, after summarizing the current state-of-the-art of the most employed theoretical methods focusing on the singlet–triplet energy difference, with the additional aim of motivating complementary studies revealing the stronger and weaker aspects of computational modelling for this cutting-edge technology. Full article

(This article belongs to the Special Issue Molecular Materials for Energy Conversion and Storage Technologies)

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