Editorial pubs.acs.org/JPCL
Emergence of New Materials for Light−Energy Conversion: Perovskites, Metal Clusters, and 2‑D Hybrids
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The Perspective by Kai Zhu and Yixin Zhao in this issue reviews the recent progress of perovskite solar cell design with a focus on solution chemistry, engineering processes, and various synthetic controls for preparing high-quality perovskite films (http://pubs.acs.org/doi/abs/10.1021/jz501983v). Zhu discusses the impact of solution-processing parameters and perovskite film architectures on the charge carrier dynamics that directly influence perovskite solar cell performance. A better understanding of structural and electronic configurations is essential in attaining the long-term stability and reproducibility of these perovskite solar cells. An earlier virtual issue on perovskite solar cells (http://pubs.acs.org/JACSbeta/jvi/issue27.html) provides additional physical chemistry insights on this emerging topic. Another area that is gaining prominence is the design of thiolate-protected metal clusters (Aun(SR)m). These magic number gold atom clusters exhibit molecular-like electronic transitions. The size-dependent photochemical properties have already been explored in metal-cluster-sensitized solar cells and photocatalytic generation of hydrogen. Negishi and co-workers present functionalization methods and discuss three representative types of magic clusters: Au25(SR)18, Au38(SR)24, and Au 1 4 4 (SR) 6 0 (http://pubs.acs.org/doi/abs/10.1021/ jz501941p). Doping with Pt, Pd, Cu, and Ag has been a convenient method to functionalize and modulate the properties of these metal clusters. In particular, doping with Ag and Au has a direct influence on photophysical properties. Whereas the majority of the energy conversion efforts with a gold nanostructure has centered on plasmonic properties, the salient energy conversion aspects of the thiolate-protected gold clusters have yet to be fully explored. It is important to think beyond plasmonics to further the utilization of gold nanostructures in light−energy conversion with greater efficiency. In their Perspective, Wang, Hwang, and co-workers discuss various strategies to functionalize exfoliated 2-D sheets with diverse inorganic, organic, bio, and polymer species (http:// pubs.acs.org/doi/abs/10.1021/jz502038g). Specifically, conductive 2-D materials such as graphene can offer new ways to enhance the electronic coupling between 2-D inorganic nanosheets and hybridized species. By tailoring the optical and electronic properties, it should be possible to design hybrid materials for solar hydrogen production and photocatalytic reduction of CO2. Although most of the initial studies point to increased performance of 2-D based hybrid materials, one needs to carefully assess long-term stability and environmental effects while designing systems for practical applications. The three Perspectives appearing in this issue focus on emerging strategies to design new materials that have potential application in the design of efficient light-harvesting assemblies. Fundamental understanding of the photoinduced processes,
he research related to light−energy conversion and storage continues to draw significant attention across various disciplines. In particular, the recent efforts of chemists and material scientists have led to the exploration of new materials for harvestings photons across visible and nearinfrared regions. Among these materials, organic metal halide perovskites (e.g., CH3NH3PbI3) stand out as a transformative material for photovoltaics. At the end of 2013, both Science and Nature highlighted photovoltaic aspects of organic metal halide perovskites as one of the major breakthroughs of the year. The solution-based approach to designing solar cells under ambient conditions has now led to a certified power conversion efficiency of 20.1%. Many research groups with prior expertise in dye-sensitized solar cells, quantum dot solar cells, and organic photovoltaics have quickly shifted their attention to perovskite solar cells. A burst of research activity in 2014 mainly focused on varying the design strategies with different mesoscopic substrates and electron- and hole-conducting layers, as well as achieving better and more stable performance. The need to understand the structural aspects, excited-state properties, charge separation and transport, doping effects, and interaction with water is likely to engage physical chemistry groups around the globe. The leadership role of J. Phys. Chem. Lett. in perovskite solar cell research publications is evidenced by an analysis of the 241 papers published in 2013 and part of 2014 (Figure 1). J. Phys.
Figure 1. Top 10 journals with papers published in 2013 and Jan−Oct, 2014 on a topic related to perovskite solar cells. Source: Web of Science (Oct 31, 2014). (Please see Supporting Information for the analysis of Web of Science data.)
Chem. Lett. published 12.9% of these papers relating to perovskite solar cells. J. Phys. Chem. Lett., with its leading share of perovskite publications (12.9%), is followed by Energy Environ. Sci. (9.1%) and APL Mater. (6.6%). Other major journals, Nano Lett., J. Am. Chem. Soc., J. Phys. Chem. C, and J. Mater. Chem. A, each have a share of ∼5% among the published papers. (See the Supporting Information for the analysis of the data obtained from the Web of Science.) © 2014 American Chemical Society
Published: December 4, 2014 4167
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The Journal of Physical Chemistry Letters
Editorial
including photon capture, charge separation, and interfacial charge transfer processes of nanomaterials, will be key in their development.
Prashant V. Kamat, Deputy Editor
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University of Notre Dame, Notre Dame, Indiana 46556, United States
ASSOCIATED CONTENT
S Supporting Information *
Number of perovskite solar-cell-related papers published in different journals (Web of Science data). This material is available free of charge via the Internet at http://pubs.acs.org.
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AUTHOR INFORMATION
Notes
Views expressed in this editorial are those of the author and not necessarily the views of the ACS.
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