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organic photovoltaic

Alberto Baggioli, Carlo A Cavallotti, Antonino Famulari
From proteins and peptides to semiconducting polymers, aliphatic chains on aromatic groups are recurring motifs in macromolecules from very diverse application fields. Fields in which molecular folding and packing determine the macroscopic physical properties that make such advanced materials appealing in the first place. Within each macromolecule, the intrinsic structure of each unit defines how it interacts with its neighbours, ultimately opening up or denying certain backbone conformations. This eventually also determines how macromolecules interact with each other...
October 18, 2016: Physical Chemistry Chemical Physics: PCCP
Atanu Jana, Masatoshi Ishida, Jung Su Park, Steffen Bähring, Jan O Jeppesen, Jonathan L Sessler
After the epochal discovery of the "organic metal", namely, tetrathiafulvalene (TTF)-7,7,8,8-tetracyano-p-quinodimethane (TCNQ) dyad in 1973, scientists have made efforts to derivatize TTF for constructing various supramolecular architectures to control the charge-transfer processes by adjusting the donor-acceptor strength of the dyads for numerous applications. The interesting inherent electronic donor properties of TTFs control the overall electrochemical properties of the supramolecular structures, leading to the construction of highly efficient optoelectronic materials, photovoltaic solar cells, organic field-effect transistors, and optical sensors...
October 18, 2016: Chemical Reviews
Yasemin Saygili, Magnus Söderberg, Norman Pellet, Fabrizio Giordano, Yiming Cao, Ana B Munoz-Garcia, Shaik Mohammed Zakeeruddin, Nick Vlachopoulos, Michele Pavone, Gerrit Boschloo, Ladislav Kavan, Jacques-E Moser, Michael Grätzel, Anders Hagfeldt, Marina Freitag
Redox mediators play a major role determining the photocurrent and the photovoltage in dye-sensitized solar cells (DSCs). To maintain the photocurrent, the reduction of oxidized dye by the redox mediator should be significantly faster than the back electron transfer between TiO2 and the oxidized dye. The driving force for dye regeneration with the redox mediator should be sufficiently low to provide high photovoltages. With our introduction of new copper complexes as promising redox mediators in DSCs both criteria are satisfied to enhance power conversion efficiencies...
October 17, 2016: Journal of the American Chemical Society
Laura Calió, Samrana Kazim, Michael Grätzel, Shahzada Ahmad
The pressure to move towards renewable energy has inspired researchers to look for ideas in photovoltaics that may lead to a major breakthrough. Recently the use of perovskites as a light harvester has lead to stunning progress. The power conversion efficiency of perovskite solar cells is now approaching parity (>22 %) with that of the established technology which took decades to reach this level of performance. The use of a hole transport material (HTM) remains indispensable in perovskite solar cells...
October 14, 2016: Angewandte Chemie
Soohyung Park, Junkyeong Jeong, Gyeongho Hyun, Minju Kim, Hyunbok Lee, Yeonjin Yi
The energy level alignments at donor/acceptor interfaces in organic photovoltaics (OPVs) play a decisive role in device performance. However, little is known about the interfacial energetics in polymer OPVs due to technical issues of the solution process. Here, the frontier ortbial line-ups at the donor/acceptor interface in high performance polymer OPVs, PTB7/PC71BM, were investigated using in situ UPS, XPS and IPES. The evolution of energy levels during PTB7/PC71BM interface formation was investigated using vacuum electrospray deposition, and was compared with that of P3HT/PC61BM...
October 13, 2016: Scientific Reports
Liangang Xiao, Song Chen, Ke Gao, Xiaobin Peng, Feng Liu, Yong Cao, Wai-Yeung Wong, Wai-Kwok Wong, Xunjin Zhu
To mimic the natural photosynthetic systems utilizing chlorophylls to absorb light and store light energy, two new porphyrin-based small molecules of PTTR and PTTCNR have been developed for photovoltaic applications. The highest power conversion efficiency of 8.21% is achieved, corresponding to a short-circuit current of 14.30 mA cm-2, open-circuit voltage of 0.82 V, and fill factor of 70.01%. The excellent device performances can be ascribed to the engineering of molecule structure and film morphology. The horizontal conjugation of 3,3''-dihexyl-terthiophene to porphyrin-core with the vertical aliphatic 2-octylundecyl peripheral substitutions, can not only effectively increase the solar flux coverage between the conventional Soret and Q bands of porphyrin unit, but also optimize molecular packing through polymorphism associated with side-chains and the linear π-conjugated backbones...
October 12, 2016: ACS Applied Materials & Interfaces
Xisheng Zhang, Dong Yang, Zhou Yang, Xiaojia Guo, Bin Liu, Xiaodong Ren, Shengzhong Frank Liu
The PEDOT:PSS is often used as the window layer in the normal structured PEDOT:PSS/c-Si hybrid solar cell (HSC), leading to significantly reduced response, especially in red and near-infrared region. By depositing the PEDOT:PSS on the rear side of the c-Si wafer, we developed an inverted structured HSC with much higher solar cell response in the red and near-infrared spectrum. Passivating the other side with hydrogenated amorphous silicon (a-Si:H) before electrode deposition, the minority carrier lifetime has been significantly increased and the power conversion efficiency (PCE) of the inverted HSC is improved to as high as 16...
October 11, 2016: Scientific Reports
Zheng Chen, Zhi-Gang Gu, Wen-Qiang Fu, Fei Wang, Jian Zhang
Organic-inorganic hybrid lead organohalide perovskites are inexpensive materials for high-efficiency photovoltaic solar cells, optical properties and superior electrical conductivity. However, the fabrication of their quantum dots (QDs) with uniform ultra-small particles is still a challenge. Here we use oriented microporous metal-organic framework (MOF) thin film prepared by liquid phase epitaxy approach as a template for CH3NH3PbI2X (X = Cl, Br and I) perovskite QDs fabrication. By introducing the PbI2 and CH3NH3X (MAX) precursors into MOF HKUST-1 (Cu3(BTC)2, BTC = 1,3,5-benzene tricarboxylate) thin film in a stepwise approach, the resulted perovskite MAPbI2X (X = Cl, Br and I) QDs with uniform diameters of 1...
October 10, 2016: ACS Applied Materials & Interfaces
Matthew B Goldey, Daniel Reid, Juan de Pablo, Giulia Galli
Establishing how the conformation of organic photovoltaic (OPV) polymers affects their electronic and transport properties is critical in order to determine design rules for new OPV materials and in particular to understand the performance enhancements recently reported for ternary blends. We report coupled classical and ab initio molecular dynamics simulations showing that polymer linkage twisting significantly reduces optical absorption efficiency, as well as hole transport rates in donor polymers. We predict that blends with components favoring planar geometries contribute to the enhancement of the overall efficiency of ternary OPVs...
September 19, 2016: Physical Chemistry Chemical Physics: PCCP
Eisuke Kawashima, Mikiya Fujii, Koichi Yamashita
The morphology of organic photovoltaics (OPVs) is a significant factor in improving performance, and establishing a method for controlling morphology is necessary. In this study, we propose a device-size simulation model, combining reptation and the dynamic Monte Carlo (DMC) algorithm, to investigate the relationship between the manufacturing process, morphology, and OPV performance. The reptation reproduces morphologies under thermal annealing, and DMC showed morphology-dependence of performance: not only short-circuit current density but also open-circuit voltage had optimal interfacial areas due to competition between exciton dissociation and charge collection...
September 29, 2016: Physical Chemistry Chemical Physics: PCCP
Felix Vüllers, Guillaume Gomard, Jan B Preinfalk, Efthymios Klampaftis, Matthias Worgull, Bryce Richards, Hendrik Hölscher, Maryna N Kavalenka
Inspired by the transparent hair layer on water plants Salvinia and Pistia, superhydrophobic flexible thin films, applicable as transparent coatings for optoelectronic devices, are introduced. Thin polymeric nanofur films are fabricated using a highly scalable hot pulling technique, in which heated sandblasted steel plates are used to create a dense layer of nano- and microhairs surrounding microcavities on a polymer surface. The superhydrophobic nanofur surface exhibits water contact angles of 166 ± 6°, sliding angles below 6°, and is self-cleaning against various contaminants...
September 26, 2016: Small
Manuel Salado, Laura Calio, Rüdiger Berger, Samrana Kazim, Shahzada Ahmad
Lead halide based perovskite solar cells are presently the flagship among the third generation solution-processed photovoltaic technologies. The organic cation part in the perovskite plays an important role in terms of crystal structure tuning from tetragonal to trigonal or pseudocubic or vice versa depending on the organic cations used, while it also displays different microstructure. In this paper, we demonstrate the influence of the organic cation part with respect to optical properties, hysteresis behavior, and stability...
October 5, 2016: Physical Chemistry Chemical Physics: PCCP
Nam-Gyu Park
Since the groundbreaking report on a solid-state perovskite solar cell employing a methylammonium lead iodide-sensitized mesoporous TiO2 film and an organic hole conducting layer in 2012 by our group, the swift surge of perovskite photovoltaics opens a new paradigm in solar-cell research. As a result, ca. 1300 peer-reviewed research articles were published in 2015. In this Inorganic Chemistry Forum on Halide Perovskite, the researches with highlights of work on perovskite solar cells in my laboratory are reviewed...
October 6, 2016: Inorganic Chemistry
LePing Yu, Cameron Shearer, Joseph Shapter
Transparent conducting films (TCFs) are a critical component in many personal electronic devices. Transparent and conductive doped metal oxides are widely used in industry due to their excellent optoelectronic properties as well as the mature understanding of their production and handling. However, they are not compatible with future flexible electronics developments where large-scale production will likely involve roll-to-roll manufacturing. Recent studies have shown that carbon nanotubes provide unique chemical, physical, and optoelectronic properties, making them an important alternative to doped metal oxides...
October 5, 2016: Chemical Reviews
Joshua C Byers, Thomas Heiser, Maksim Skorobogatiy, Oleg A Semenikhin
A series of encapsulated and non-encapsulated bulk heterojunction photovoltaic devices containing poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) with different P3HT:PCBM ratios were investigated using traditional steady state as well as non-steady state intensity modulated photocurrent spectroscopy (IMPS) techniques. The steady state J-V measurements showed that PCBM content did not have a significant effect on the efficiency for freshly prepared devices, whereas aged non-encapsulated devices exhibited a strong dependence on PCBM content...
October 5, 2016: ACS Applied Materials & Interfaces
Bobo Li, Chaoyue Zheng, Huan Liu, Jie Zhu, Hongmei Zhang, Deqing Gao, Wei Huang
In hybrid organic-inorganic perovskite solar cells (PSCs), interfacial engineering can efficiently improve the photovoltaic performance. In this work, the planar π-conjugated porphyrin, zinc(II) 5,10,15,20-tetrakis[5-(p-acetylthiopentyloxy)phenyl]porphyrin, was developed to modify the interface between poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) and perovskite. The modified devices increased their highest power conversion efficiency (PCE) to 14.05% relative to 11.35% for the reference devices without modification...
October 4, 2016: ACS Applied Materials & Interfaces
G M Paternò, M W A Skoda, Robert Dalgliesh, F Cacialli, V García Sakai
Controlling the nanoscale arrangement in polymer-fullerene organic solar cells is of paramount importance to boost the performance of such promising class of photovoltaic diodes. In this work, we use a pseudo-bilayer system made of poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene (PBTTT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), to acquire a more complete understanding of the diffusion and intercalation of the fullerene-derivative within the polymer layer. By exploiting morphological and structural characterisation techniques, we observe that if we increase the film solidification time the polymer develops a higher crystalline order, and, as a result, it does not allow fullerene molecules to intercalate between the polymer side-chains...
October 4, 2016: Scientific Reports
Chang Liu, Lin Zhang, Liangang Xiao, Xiaobin Peng, Yong Cao
By doping ZnO with porphyrin small molecules (FNEZnP-OE and FNEZnP-T) as cathode electron transport layers (ETLs), the inverted polymer solar cells (i-PSC) with PTB7:PC71BM (PTB7: polythieno[3,4-b]-thiophene-co-benzodithiophene, PC71BM: [6, 6]-phenyl-C71-butyric acid methyl ester) as the active materials exhibit enhanced device performance. While the power conversion efficiency (PCE) of the PSCs with pure ZnO ETL is 7.52%, that of the devices with FNEZnP-T-doped ZnO ETL shows a slightly improved PCE of 8.09%, and that of the PSCs with FNEZnP-OE-doped ZnO ETL is further enhanced up to 9...
October 3, 2016: ACS Applied Materials & Interfaces
Wei-Cheng Su, Chih-Chien Lee, Ya-Ze Li, Shun-Wei Liu
We demonstrated that the open-circuit voltage (VOC) of rubrene/C60 organic photovoltaic (OPV) devices can be substantially improved by changing the rubrene thickness. A shoulder exhibited in a range of 500-550 nm was observed. This result indicated that the singlet excitons of rubrene were increased when the thickness of the rubrene layer was increased. Capacitance-voltage measurements were conducted for estimating the built-in potential of the devices. The calculated VOC was higher than that of the experiment, thus indicating that energetic losses occurred in the devices...
October 3, 2016: ACS Applied Materials & Interfaces
Mannix P Balanay, Kyu-Seok Choi, Sang Hee Lee, Dong Hee Kim
Two spiro-like organic dyes linked at the thiophene bridge (KS-11 and KS-12) together with the original rod-shaped D-π-A configuration (C1) were designed, synthesized, and characterized based on their electronic structure, and determine the photophysical and photovoltaic properties for its application in dye-sensitized solar cells. Compared to C1, the double D-π-A spiro-like configuration, which consists of two separated light-harvesting moieties, was found to be beneficial to photocurrent generation provided that they are separated properly to prevent intramolecular exciton annihilation...
September 22, 2016: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
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