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In conventional fullerene-based organic photovoltaics (OPVs), in which the excited electrons from the donor are transferred to the acceptor, the electron charge transfer state (eECT) that electrons pass through has a great influence on the device’s performance. In a bulk-heterojunction (BHJ) system based on a low bandgap non-fullerene acceptor (NFA), however, a hole charge transfer state (hECT) from the acceptor to the donor has a greater influence on the device’s performance. The accurate determination of hECT is essential for achieving further enhancement in the performance of non-fullerene organic solar cells. However, the discovery of a method to determine the exact hECT remains an open challenge. Here, we suggest a simple method to determine the exact hECT level via deconvolution of the EL spectrum of the BHJ blend (ELB). To generalize, we have applied our ELB deconvolution method to nine different BHJ systems consisting of the combination of three donor polymers (PM6, PBDTTPD-HT, PTB7-Th) and three NFAs (Y6, IDIC, IEICO-4F). Under the conditions that (i) absorption of the donor and acceptor are separated sufficiently, and (ii) the onset part of the external quantum efficiency (EQE) is formed solely by the contribution of the acceptor only, ELB can be deconvoluted into the contribution of the singlet recombination of the acceptor and the radiative recombination via hECT. Through the deconvolution of ELB, we have clearly decided which part of the broad ELB spectrum should be used to apply the Marcus theory. Accurate determination of hECT is expected to be of great help in fine-tuning the energy level of donor polymers and NFAs by understanding the charge transfer mechanism clearly.

Summary: Although the power conversion efficiency (PCE) of organic photovoltaic (OPV) devices has recently improved to more than 16%, halogenated solution processes are typically employed to obtain optimal performance. However, halogenated processing is harmful to health and the environment, which can be a significant obstacle to commercialization. Therefore, development of active materials processable under halogen-free conditions is of great importance in this field. In this study, a 16.04% OPV device, processed under halogen-free conditions, is developed by employing a new active-blend system, PBDTTPD-HT:BTP-2F-BO. It is highly soluble in halogen-free solvents, forming a preferential bulk-heterojunction morphology. The PBDTTPD-HT:BTP-2F-BO device achieves a PCE comparable with current state-of-the-art devices based on PBDB-TF:BTP-4F (also known as PM6:Y6) using a conventional halogenated process (16.40% versus 16.33%). Furthermore, it demonstrates a significantly higher PCE than the PBDB-TF:BTP-4F device with a halogen-free process (16.04% versus 9.70%).

Abstract A charge transport layer based on transition metal‐oxides prepared by an anhydrous sol–gel method normally requires high‐temperature annealing to achieve the desired quality. Although annealing is not a difficult process in the laboratory, it is definitely not a simple process in mass production, such as roll‐to‐roll, because of the inevitable long cooling step that follows. Therefore, the development of an annealing‐free solution‐processable metal‐oxide is essential for the large‐scale commercialization. In this work, a room‐temperature processable annealing‐free “aqueous” MoOx solution is developed and applied in non‐fullerene PBDB‐T‐2F:Y6 solar cells. By adjusting the concentration of water in the sol–gel route, an annealing‐free MoOx with excellent electrical properties is successfully developed. The PBDB‐T‐2F:Y6 solar cell with the general MoOx prepared by the anhydrous sol–gel method shows a low efficiency of 7.7% without annealing. If this anhydrous MoOx is annealed at 200 °C, the efficiency is recovered to 17.1%, which is a normal value typically observed in conventional structure PBDB‐T‐2F:Y6 solar cells. However, without any annealing process, the solar cell with aqueous MoOx exhibits comparable performance of 17.0%. In addition, the solar cell with annealing‐free aqueous MoOx exhibits better performance and stability without high‐temperature annealing compared to the solar cells with PEDOT:PSS.

In conventional fullerene-based organic photovoltaics (OPVs), in which the excited electrons from the donor are transferred to the acceptor, the electron charge transfer state (eECT) that electrons pass through has a great influence on the device's performance. In a bulk-heterojunction (BHJ) system based on a low bandgap non-fullerene acceptor (NFA), however, a hole charge transfer state (hECT) from the acceptor to the donor has a greater influence on the device's performance. The accurate determination of hECT is essential for achieving further enhancement in the performance of non-fullerene organic solar cells. However, the discovery of a method to determine the exact hECT remains an open challenge. Here, we suggest a simple method to determine the exact hECT level via deconvolution of the EL spectrum of the BHJ blend (ELB). To generalize, we have applied our ELB deconvolution method to nine different BHJ systems consisting of the combination of three donor polymers (PM6, PBDTTPD-HT, PTB7-Th) and three NFAs (Y6, IDIC, IEICO-4F). Under the conditions that (i) absorption of the donor and acceptor are separated sufficiently, and (ii) the onset part of the external quantum efficiency (EQE) is formed solely by the contribution of the acceptor only, ELB can be deconvoluted into the contribution of the singlet recombination of the acceptor and the radiative recombination via hECT. Through the deconvolution of ELB, we have clearly decided which part of the broad ELB spectrum should be used to apply the Marcus theory. Accurate determination of hECT is expected to be of great help in fine-tuning the energy level of donor polymers and NFAs by understanding the charge transfer mechanism clearly. [ABSTRACT FROM AUTHOR]

The photoactive layer of non‐fullerene organic solar cells (OSCs) generally consists of a low band‐gap acceptor and conjugated polymer with a deep highest occupied molecular orbital (HOMO) because the hole transfer from the acceptor to the donor as well as the electron transfer from the donor polymer to the acceptor is very important to achieve better performance. Therefore, energy level matching between the HOMO of the donor polymer and the work‐function (WF) of the hole transport layer is required. Since the intrinsic p‐type NiO has a lower WF value, the efficiency of NiO‐based PBDB‐T‐2F:Y6 OSCs is somewhat suppressed. In this work, the energy barrier between the NiO (5.1 eV) and HOMO of PBDB‐T‐2F (5.6 eV) by modifying the NiO surface using a 4‐(trifluoromethyl)benzoic acid (PTF‐BOA) dipole layer (NiO‐PTF‐BOA) is successfully eliminated. The carboxyl group of PTF‐BOA is bonded with Ni atoms on the NiO surface, while the CF3 group attracts electrons, thus resulting in a partial negative charge on the CF3 side. This PTF‐BOA dipole layer induces the vacuum level upshift thus enhancing the work function of NiO‐PTF‐BOA to 5.5 eV. The PBDB‐T‐2F:Y6 OSCs with NiO‐PTF‐BOA exhibit an efficiency of 16.36%, which is the highest reported efficiency for NiO‐based OSCs. [ABSTRACT FROM AUTHOR]

Background: Although studies have described factors associated with failed magnetic resonance elastography (MRE), little is known about what factors influence usable elastography data. Purpose: To identify factors that have a negative impact on percent measurable liver volume (pMLV), defined as the proportion of usable liver elastography data relative to the volume of imaged liver in patients undergoing MRE. Study Type: Retrospective. Subjects: A total of 264 patients (n = 132 males, n = 132 females; mean age = 57 years) with suspected or known chronic liver disease underwent MRE paired with a liver protocol MRI. Field strength/Sequence: MRE was performed on a single 1.5 T scanner using a two‐dimensional gradient‐recalled echo phase‐contrast sequence with a passive acoustic driver overlying the right hemiliver. Assessment: Stiffness maps (usable data at 95% confidence) and liver contours on magnitude images of the MRE acquisition were manually traced and used to assess mean stiffness and pMLV. Hepatic fat fraction and R2* values were also calculated. The distance from the acoustic wave generator on the skin surface to the liver edge was measured. Two radiologists performed the MR analyses with 50 overlapping cases for inter‐reader analysis. Statistical Tests: Linear regression was performed to identify factors significantly associated with pMLV. Intraclass correlation was performed for inter‐reader reliability. Results: pMLV was 31% ± 20% (range 0%–86%). Complete MRE failure (i.e. pMLV = 0%) occurred in 10 patients (4%). Multivariate linear regression identified higher hepatic fat fraction, R2*, BMI, and driver‐to‐liver surface distance; male sex; and lower mean liver stiffness was significantly independently associated with lower pMLV. Intraclass correlation for pMLV was 0.96, suggestive of excellent reliability. Data Conclusion: Higher fat fraction, R2*, BMI, driver‐to‐liver surface distance, male sex, and lower mean liver stiffness were associated with lower pMLV. Optimization of image acquisition parameters and driver placement may improve MRE quality, and pMLV likely serves as a diagnostic utility quality control metric. Level of Evidence: 3 Technical Efficacy Stage: 2 [ABSTRACT FROM AUTHOR]

In early studies on organic solar cells with high conductivity PEDOT:PSS, the contact between ITO and PEDOT:PSS was considered ohmic. However, because low-conductivity PEDOT:PSS (such as AI4083) is mainly utilized in contemporary solar cells, the contact between ITO and PEDOT:PSS is not ohmic anymore. Despite the high possibility that there are serious interface problems, little attention has been paid to the interface between PEDOT:PSS and ITO. Most of the previous studies of interfaces in organic solar cells have focused on the interface between the active and charge transport layers. In this work, we have employed a conjugated polyelectrolyte that uses potassium poly[9,9-bis(3′-sulfonatopropyl)fluorene-alt-(9-(2,7-diethylheptyl)-carboazole)] (WPFSCz-) between ITO and low-conductivity PEDOT:PSS to overcome complicated organic–inorganic interfacial problems. The insertion of the WPFSCz- layer provides substantial advantages in the operation of polymer solar cells. First, the inserted WPFSCz- layer modifies the work-function of ITO, thereby forming an effective cascading energy alignment, which is favorable for good hole transport. Second, the introduction of the WPFSCz- layer eliminates interfacial trap sites. The reduction in traps reduces recombination losses at the interface, resulting in an improvement in the fill factor. These effects result in a significant increase in the efficiency of non-fullerene solar cells based on PM6 and Y6, from 15.86 to 17.34%. In addition, we have found that the problem of the interface in contact with ITO occurs not only in PEDOT:PSS, but also in oxide-based charge transport layers. We have confirmed that the insertion of the WPFSCz- layer between ITO and an MoO3 (or ZnO) charge transport layer shows the same positive results. [ABSTRACT FROM AUTHOR]

A charge transport layer based on transition metal‐oxides prepared by an anhydrous sol–gel method normally requires high‐temperature annealing to achieve the desired quality. Although annealing is not a difficult process in the laboratory, it is definitely not a simple process in mass production, such as roll‐to‐roll, because of the inevitable long cooling step that follows. Therefore, the development of an annealing‐free solution‐processable metal‐oxide is essential for the large‐scale commercialization. In this work, a room‐temperature processable annealing‐free "aqueous" MoOx solution is developed and applied in non‐fullerene PBDB‐T‐2F:Y6 solar cells. By adjusting the concentration of water in the sol–gel route, an annealing‐free MoOx with excellent electrical properties is successfully developed. The PBDB‐T‐2F:Y6 solar cell with the general MoOx prepared by the anhydrous sol–gel method shows a low efficiency of 7.7% without annealing. If this anhydrous MoOx is annealed at 200 °C, the efficiency is recovered to 17.1%, which is a normal value typically observed in conventional structure PBDB‐T‐2F:Y6 solar cells. However, without any annealing process, the solar cell with aqueous MoOx exhibits comparable performance of 17.0%. In addition, the solar cell with annealing‐free aqueous MoOx exhibits better performance and stability without high‐temperature annealing compared to the solar cells with PEDOT:PSS. [ABSTRACT FROM AUTHOR]

Although the power conversion efficiency (PCE) of inorganic perovskite‐based solar cells (PSCs) is considerably less than that of organic‐inorganic hybrid PSCs due to their wider bandgap, inorganic perovskites are great candidates for the front cell in tandem devices. Herein, the low‐temperature solution‐processed two‐terminal hybrid tandem solar cell devices based on spectrally matched inorganic perovskite and organic bulk heterojunction (BHJ) are demonstrated. By matching optical properties of front and back cells using CsPbI2Br and PTB7‐Th:IEICO‐4F BHJ as the active materials, a remarkably enhanced stabilized PCE (18.04%) in the hybrid tandem device as compared to that of the single‐junction device (9.20% for CsPbI2Br and 10.45% for PTB7‐Th:IEICO‐4F) is achieved. Notably, the PCE of the hybrid tandem device is thus far the highest PCE among the reported tandem devices based on perovskite and organic material. Moreover, the long‐term stability of inorganic perovskite devices under humid conditions is improved in the hybrid tandem device due to the hydrophobicity of the PTB7‐Th:IEICO‐4F back cell. In addition, the potential promise of this type of hybrid tandem device is calculated, where a PCE of as much as ≈28% is possible by improving the external quantum efficiency and reducing energy loss in the sub‐cells. [ABSTRACT FROM AUTHOR]

Due to their fabulous performance, porphyrins are considered to be emerging materials for dye-sensitized solar cell applications (DSSCs). Herein, we have designed and synthesised four novel porphyrin sensitizers tethered with a triphenylimidazole group as the donor, a porphyrin macrocycle as the π-spacer and 4-ethynyl phenyl (LG15), 5-ethynylthiophene (LG16), 2,1,3-benzothiadiazole (BTD)-phenyl (LG17), and BTD-thiophene (LG18) as auxiliary acceptors and either a carboxylic acid or cyanoacrylic acid anchoring group, which resembles the structure of a donor–π-bridge–acceptor (D–π–A). The absorption spectra of LG17 and LG18 are red-shifted, when compared to LG15 and LG16, due to the presence of extended π-conjugation of the BDT group in its molecular structure. The red-shifted absorption spectra of LG17 and LG18 result in highest efficiency of 10.11% and 10.51%, respectively. Optical and electrochemical properties, and Density Functional Theory calculations of LG15–LG18, suggested that LG18 exhibits strong absorption and optimized lowest unoccupied molecular orbital (LUMO) aids the injection of electrons very effectively from the excited state of the dye into the TiO2 conduction band. Both LG17 and LG18 exhibit broad incident to photon conversion efficiency (IPCE) and the onset extends up to 950 nm, with ＞80% at 700 nm. Current density–voltage (J–V) curves of LG15–LG18 revealed that LG17 and LG18 exhibit highest short-circuit current density of 20.64 and 21.43 mA cm−2 resulting in power conversion efficiency (PCE) of 10.11% and 10.51%, respectively, in a liquid I−/I3− redox couple electrolyte. Bulky donor groups, π-spacer length and anchoring groups have significantly contributed to achieving high efficiency in a liquid redox shuttle that can be helpful to make efficient DSSCs for future generations. We have adopted intensity modulated photovoltage spectroscopy and nanosecond laser flash photolysis spectroscopy to explain the PCE and molecular structure relationship of the LG15–LG18 sensitizers. [ABSTRACT FROM AUTHOR]

The electrochemical water oxidation ability of complexes 5,15‐diphenylporphinatonickel(II) (A) and 5,15‐bis(3,5‐di‐tert‐butylphenyl)porphinatonickel(II) (B) in the oxygen evolution reaction (OER) have been investigated in an alkaline medium. Complex B was found to be kinetically and thermodynamically more active than complex A. The overpotential and Tafel slope of complex B are lower than those of complex A by 30 mV and around 45 mV/decade, respectively, which supports the higher activity of B. Moreover, stability tests endorse the sustainability of both samples under alkaline conditions. It has been found that the 3,5‐di‐tert‐butylphenyl substituent in B plays a decisive role in achieving a better OER onset potential and current than that obtained with A, which is a result of the modulation of the structural parameters of B. Furthermore, the measured OER activities of A and B have been correlated with their molecular arrangement as well as differences in their bonding characteristics and dipole moments. For further insight, the obtained results have been confirmed by a theoretical study. [ABSTRACT FROM AUTHOR]

Co-sensitization is a popular route towards improved efficiency and stability of dye-sensitized solar cells (DSSCs). In this context, the power conversion efficiency (PCE) values of DSSCs incorporating Ru- and porphyrin-based dyes can be improved from 8-11 % to 11-14 % after the addition of additives, co-adsorbents, and co-sensitizers that reduce aggregation and charge recombination in the device. Among the three supporting material types, co-sensitizers play a major role to enhance the performance and stability of DSSCs, which is requried for commercialization. In this Minireview, we highlight the role co-sensitizers play in improving photovoltaic performance of devices containing Ru- and porphyrin-based sensitizers. [ABSTRACT FROM AUTHOR]

Tailgut cysts are congenital lesions that arise from the primitive hindgut in the true embryonic tail but fail to regress during gestation. These lesions are rare and more frequently encountered later in life and more commonly in women, and are the most common primary retrorectal tumor. Tailgut cysts may be asymptomatic or cause rectal bleeding, pain, or symptoms related to mass effect on the rectum or bladder. Pathologically, tailgut cysts are typically multilocular, lined with a variety of epithelial cell types, and are most frequently benign. Imaging is the linchpin of diagnosis due risks associated with biopsy. The purpose of this pictorial review is to present the spectrum of imaging findings associated with tailgut cysts on CT and MRI with focus on the use of advanced MRI and diffusion-weighted imaging. We present case examples of tailgut cysts, their CT and MR imaging findings, and diagnostic and management considerations. [ABSTRACT FROM AUTHOR]

Picture archiving and communication systems (PACS) play a critical role in radiology. This paper presents the criteria important to PACS administrators for selecting a PACS. A set of criteria are identified and organized into an integrative hierarchical framework. Survey responses from 48 administrators are used to identify the relative weights of these criteria through an analytical hierarchy process. The five main dimensions for PACS selection in order of importance are system continuity and functionality, system performance and architecture, user interface for workflow management, user interface for image manipulation, and display quality. Among the subdimensions, the highest weights were assessed for security, backup, and continuity; tools for continuous performance monitoring; support for multispecialty images; and voice recognition/transcription. PACS administrators' preferences were generally in line with that of previously reported results for radiologists. Both groups assigned the highest priority to ensuring business continuity and preventing loss of data through features such as security, backup, downtime prevention, and tools for continuous PACS performance monitoring. PACS administrators' next high priorities were support for multispecialty images, image retrieval speeds from short-term and long-term storage, real-time monitoring, and architectural issues of compatibility and integration with other products. Thus, next to ensuring business continuity, administrators' focus was on issues that impact their ability to deliver services and support. On the other hand, radiologists gave high priorities to voice recognition, transcription, and reporting; structured reporting; and convenience and responsiveness in manipulation of images. Thus, radiologists' focus appears to be on issues that may impact their productivity, effort, and accuracy. [ABSTRACT FROM AUTHOR]

Two novel sterically demanding zinc phthalocyanines were synthesized and characterized. Their optical and electrochemical properties were investigated in detail. The emission spectra were recorded in different solvents and the fluorescence yields obtained were in the range of 0.2–0.3 while time-resolved fluorescence data revealed radiative lifetimes of typically few ns. Nonlinear optical (NLO) properties were also evaluated at wavelengths of 600, 640, 680, and 800 nm using picosecond (∼1.5 ps) pulses and further studies with femtosecond (∼140 fs) pulses at 800 and 780 nm were also performed. Two-photon absorption (2PA) and saturable absorption (SA) were the dominant nonlinear absorption mechanisms observed with ps/fs excitation at different wavelengths in the visible spectral region. NLO coefficients were extracted from ps/fs closed and open aperture Z-scan measurements. Large two-photon absorption cross-sections of ∼14 000 GM and n2 values in the range of 1–7 × 10−16 cm2 W−1 were retrieved for these molecules from the ps Z-scan data. The excited state decay dynamics were investigated using degenerate pump-probe experiments with ∼70 fs pulses near 600 nm. Double exponential fits of the pump-probe data suggested two decay times for both molecules investigated. [ABSTRACT FROM AUTHOR]

Upper-extremity venous thrombosis often presents as unilateral arm swelling. The differential diagnosis includes lesions compressing the veins and causing a functional venous obstruction, venous stenosis, an infection causing edema, obstruction of previously functioning lymphatics, or the absence of sufficient lymphatic channels to ensure effective drainage. The following recommendations are made with the understanding that venous disease, specifically venous thrombosis, is the primary diagnosis to be excluded or confirmed in a patient presenting with unilateral upper-extremity swelling. Contrast venography remains the best reference-standard diagnostic test for suspected upper-extremity acute venous thrombosis and may be needed whenever other noninvasive strategies fail to adequately image the upper-extremity veins. Duplex, color flow, and compression ultrasound have also established a clear role in evaluation of the more peripheral veins that are accessible to sonography. Gadolinium contrast–enhanced MRI is routinely used to evaluate the status of the central veins. Delayed CT venography can often be used to confirm or exclude more central vein venous thrombi, although substantial contrast loads are required. The ACR Appropriateness Criteria® are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment. [ABSTRACT FROM AUTHOR]

Picture archiving and communication systems (PACS) play a critical role in radiology. This paper presents the criteria important to PACS administrators for selecting a PACS. A set of criteria are identified and organized into an integrative hierarchical framework. Survey responses from 48 administrators are used to identify the relative weights of these criteria through an analytical hierarchy process. The five main dimensions for PACS selection in order of importance are system continuity and functionality, system performance and architecture, user interface for workflow management, user interface for image manipulation, and display quality. Among the subdimensions, the highest weights were assessed for security, backup, and continuity; tools for continuous performance monitoring; support for multispecialty images; and voice recognition/transcription. PACS administrators' preferences were generally in line with that of previously reported results for radiologists. Both groups assigned the highest priority to ensuring business continuity and preventing loss of data through features such as security, backup, downtime prevention, and tools for continuous PACS performance monitoring. PACS administrators' next high priorities were support for multispecialty images, image retrieval speeds from short-term and long-term storage, real-time monitoring, and architectural issues of compatibility and integration with other products. Thus, next to ensuring business continuity, administrators' focus was on issues that impact their ability to deliver services and support. On the other hand, radiologists gave high priorities to voice recognition, transcription, and reporting; structured reporting; and convenience and responsiveness in manipulation of images. Thus, radiologists' focus appears to be on issues that may impact their productivity, effort, and accuracy. [ABSTRACT FROM AUTHOR]

A charge transport layer based on transition metal‐oxides prepared by an anhydrous sol–gel method normally requires high‐temperature annealing to achieve the desired quality. Although annealing is not a difficult process in the laboratory, it is definitely not a simple process in mass production, such as roll‐to‐roll, because of the inevitable long cooling step that follows. Therefore, the development of an annealing‐free solution‐processable metal‐oxide is essential for the large‐scale commercialization. In this work, a room‐temperature processable annealing‐free "aqueous" MoOx solution is developed and applied in non‐fullerene PBDB‐T‐2F:Y6 solar cells. By adjusting the concentration of water in the sol–gel route, an annealing‐free MoOx with excellent electrical properties is successfully developed. The PBDB‐T‐2F:Y6 solar cell with the general MoOx prepared by the anhydrous sol–gel method shows a low efficiency of 7.7% without annealing. If this anhydrous MoOx is annealed at 200 °C, the efficiency is recovered to 17.1%, which is a normal value typically observed in conventional structure PBDB‐T‐2F:Y6 solar cells. However, without any annealing process, the solar cell with aqueous MoOx exhibits comparable performance of 17.0%. In addition, the solar cell with annealing‐free aqueous MoOx exhibits better performance and stability without high‐temperature annealing compared to the solar cells with PEDOT:PSS. [ABSTRACT FROM AUTHOR]