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Author

Russel Ross

Other affiliations: Georgetown University
Bio: Russel Ross is an academic researcher from University of Washington. The author has contributed to research in topics: Fullerene & Acceptor. The author has an hindex of 2, co-authored 2 publications receiving 637 citations. Previous affiliations of Russel Ross include Georgetown University.

Papers
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Journal ArticleDOI
TL;DR: This work clears a path towards higher PCEs in OPV devices by demonstrating that high-yield charge separation can occur with OPV systems that have a reduced donor/acceptor lowest unoccupied molecular orbital energy offset.
Abstract: A limiting factor of the power conversion efficiencies of organic photovoltaic devices is low voltage output Methano derivatives of the trimetallic endohedral fullerene Lu3N@C80 have now been synthesized and used as the acceptor in organic photovoltaics The open circuit voltage of the devices is significantly above those made using alternative fullerenes So far, one of the fundamental limitations of organic photovoltaic (OPV) device power conversion efficiencies (PCEs) has been the low voltage output caused by a molecular orbital mismatch between the donor polymer and acceptor molecules Here, we present a means of addressing the low voltage output by introducing novel trimetallic nitride endohedral fullerenes (TNEFs) as acceptor materials for use in photovoltaic devices TNEFs were discovered in 1999 by Stevenson et al 1; for the first time derivatives of the TNEF acceptor, Lu3N@C80, are synthesized and integrated into OPV devices The reduced energy offset of the molecular orbitals of Lu3N@C80 to the donor, poly(3-hexyl)thiophene (P3HT), reduces energy losses in the charge transfer process and increases the open circuit voltage (Voc) to 260 mV above reference devices made with [6,6]-phenyl-C61-butyric methyl ester (C60-PCBM) acceptor PCEs >4% have been observed using P3HT as the donor material This work clears a path towards higher PCEs in OPV devices by demonstrating that high-yield charge separation can occur with OPV systems that have a reduced donor/acceptor lowest unoccupied molecular orbital energy offset

577 citations

Journal ArticleDOI
TL;DR: In this article, the influence of 1-(3-hexoxycarbonyl)propyl-1-phenyl-[6,6]-Lu3N@C81, Lu3N/C80-PCBH, a novel acceptor material, has on active layer morphology and the performance of organic photovoltaic (OPV) devices using this material is reported.
Abstract: Here the influence that 1-(3-hexoxycarbonyl)propyl-1-phenyl-[6,6]-Lu3N@C81, Lu3N@C80–PCBH, a novel acceptor material, has on active layer morphology and the performance of organic photovoltaic (OPV) devices using this material is reported. Polymer/fullerene blend films with poly(3-hexylthiophene), P3HT, donor material and Lu3N@C80–PCBH acceptor material are studied using absorption spectroscopy, grazing incident X-ray diffraction and photocurrent spectra of photovoltaic devices. Due to a smaller molecular orbital offset the OPV devices built with Lu3N@C80–PCBH display increased open circuit voltage over empty cage fullerene acceptors. The photovoltaic performance of these metallo endohedral fullerene blend films is found to be highly impacted by the fullerene loading. The results indicate that the optimized blend ratio in a P3HT matrix differs from a molecular equivalent of an optimized P3HT/[6,6]-phenyl-C61-butyric methyl ester, C60–PCBM, active layer, and this is related to the physical differences of the C80 fullerene. The influence that active layer annealing has on the OPV performance is further evaluated. Through properly matching the film processing and the donor/acceptor ratio, devices with power conversion efficiency greater than 4% are demonstrated.

99 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, a review summarizes recent progress in the development of polymer solar cells and provides a synopsis of major achievements in the field over the past few years, while potential future developments and the applications of this technology are also briefly discussed.
Abstract: This Review summarizes recent progress in the development of polymer solar cells. It covers the scientific origins and basic properties of polymer solar cell technology, material requirements and device operation mechanisms, while also providing a synopsis of major achievements in the field over the past few years. Potential future developments and the applications of this technology are also briefly discussed.

3,832 citations

Journal ArticleDOI
TL;DR: An outlook is presented on what will be required to drive this young photovoltaic technology towards the next major milestone, a 10% power conversion efficiency, considered by many to represent the efficiency at which OPV can be adopted in wide-spread applications.
Abstract: Solution-processed bulk-heterojunction solar cells have gained serious attention during the last few years and are becoming established as one of the future photovoltaic technologies for low-cost power production. This article reviews the highlights of the last few years, and summarizes today's state-of-the-art performance. An outlook is given on relevant future materials and technologies that have the potential to guide this young photovoltaic technology towards the magic 10% regime. A cost model supplements the technical discussions, with practical aspects any photovoltaic technology needs to fulfil, and answers to the question as to whether low module costs can compensate lower lifetimes and performances.

3,084 citations

Journal ArticleDOI
TL;DR: This review summarizes the developments in small molecular donors, acceptors, and donor-acceptor dyad systems for high-performance multilayer, bulk heterojunction, and single-component OPVs and focuses on correlations of molecular chemical structures with properties, such as absorption, energy levels, charge mobilities, and photovoltaic performances.
Abstract: Organic photovoltaic cells (OPVs) are a promising cost-effective alternative to silicon-based solar cells, and possess light-weight, low-cost, and flexibility advantages. Significant progress has been achieved in the development of novel photovoltaic materials and device structures in the last decade. Nowadays small molecular semiconductors for OPVs have attracted considerable attention, due to their advantages over their polymer counterparts, including well-defined molecular structure, definite molecular weight, and high purity without batch to batch variations. The highest power conversion efficiencies of OPVs based on small molecular donor/fullerene acceptors or polymeric donor/fullerene acceptors are up to 6.7% and 8.3%, respectively, and meanwhile nonfullerene acceptors have also exhibited some promising results. In this review we summarize the developments in small molecular donors, acceptors (fullerene derivatives and nonfullerene molecules), and donor–acceptor dyad systems for high-performance multilayer, bulk heterojunction, and single-component OPVs. We focus on correlations of molecular chemical structures with properties, such as absorption, energy levels, charge mobilities, and photovoltaic performances. This structure–property relationship analysis may guide rational structural design and evaluation of photovoltaic materials (253 references).

1,515 citations

Journal ArticleDOI
TL;DR: The research community has made great progress in the field of bulk heterojunction (BHJ) polymer solar cells since its inception in 1995 as mentioned in this paper and the power conversion efficiency (PCE) has increased from 1% in the 1990s to over 8% just recently.
Abstract: The research on the polymer-based solar cells (PSCs) has attracted an increasing amount of attention in recent years because PSCs pose potential advantages over mainstream inorganic-based solar cells, such as significantly reduced material/fabrication costs, flexible substrates, and light weight of finished solar cells. The research community has made great progress in the field of bulk heterojunction (BHJ) polymer solar cells since its inception in 1995. The power conversion efficiency (PCE), a key parameter to assess the performance of solar cells, has increased from 1% in the 1990s to over 8% just recently. These great advances are mainly fueled by the development of conjugated polymers used as the electron-donating materials in BHJ solar cells. In this Perspective, we first briefly review the progress on the design of conjugated polymers for polymer solar cells in the past 16 years. Since a conjugated polymer can be arbitrarily divided into three constituting components—the conjugated backbone, the si...

1,403 citations

Journal ArticleDOI
TL;DR: It is demonstrated that charge-transfer absorption and emission are shown to be related to each other and Voc is determined by the formation of these states in accordance with the assumptions of the detailed balance and quasi-equilibrium theory.
Abstract: The increasing amount of research on solution-processable, organic donor-acceptor bulk heterojunction photovoltaic systems, based on blends of conjugated polymers and fullerenes has resulted in devices with an overall power-conversion efficiency of 6%. For the best devices, absorbed photon-to-electron quantum efficiencies approaching 100% have been shown. Besides the produced current, the overall efficiency depends critically on the generated photovoltage. Therefore, understanding and optimization of the open-circuit voltage (Voc) of organic solar cells is of high importance. Here, we demonstrate that charge-transfer absorption and emission are shown to be related to each other and Voc in accordance with the assumptions of the detailed balance and quasi-equilibrium theory. We underline the importance of the weak ground-state interaction between the polymer and the fullerene and we confirm that Voc is determined by the formation of these states. Our work further suggests alternative pathways to improve Voc of donor-acceptor devices.

1,121 citations