Inert gamma degradation of 46 organic hole transport materials reveal a high average ionizing dose tolerance of more than 10 kGy, with BODIPY molecules exceeding 100 kGy.

In this work were made the synthesis of symmetric and asymmetric pyridine–diarylamine derivatives through Buchwald–Hartwig cross-coupling reactions using 2,6- and 2,5-dibromopyridine cores functionalized with bis(4-methoxyphenyl)amine (DPA) and iminodibenzyl (IMB) donor units. The influence of molecular symmetry and donor structure on the electronic and optical properties of the resulting compounds was systematically investigated through photophysical, electrochemical, and theoretical studies. UV–Vis spectroscopy revealed absorption bands associated with π–π* transitions and intramolecular charge-transfer (ICT) processes, with the asymmetric 2,5-substituted derivatives exhibiting red-shifted absorption relative to their symmetric 2,6 analogues, indicating enhanced donor–acceptor electronic communication. Fluorescence measurements showed blue emission with quantum yields strongly dependent on both substitution pattern and donor rigidity. Solvatochromic studies confirmed the presence of excited-state charge-transfer processes, while cyclic and square-wave voltammetry demonstrated that asymmetric substitution significantly modifies the frontier molecular orbital energies, leading to improved electron-donating character. Density functional theory (DFT) and time-dependent DFT calculations successfully reproduced the experimental optical behavior and revealed distinct ICT mechanisms depending on the substitution pattern. In the 2,5-substituted derivatives, electron transfer occurs from the diarylamine donor toward the pyridine core, whereas an opposite charge-transfer direction was observed for the 2,6-substituted systems. These findings provide valuable insights into the structure–property relationships governing pyridine–diarylamine conjugated systems and highlight molecular symmetry as a key parameter for tuning their optoelectronic behavior.

Perovskite solar cells (PSCs) have recently achieved over 26 % power conversion efficiency, challenging the dominance of silicon-based alternatives. This progress is significantly driven by innovations in hole transport materials (HTMs), which notably influence the efficiency and stability of PSCs. However, conventional organic HTMs like Spiro-OMeTAD and PTAA, although highly efficient, suffer from thermal degradation, moisture ingress, and high cost. This study explores the potential of iminodibenzyl, a moiety known for its strong electron-donating capabilities in pharmaceutical applications, as a novel HTM. A series of fluorene-based derivatives incorporating iminodibenzyl (TMF-2 and TDF-2) and diphenylamine (TMF-1 and TDF-1) units were synthesized and characterized. The new HTMs demonstrated commendable optical, electrochemical, and thermal properties, as well as enhanced photostability. Among them, TDF-2 achieved a power conversion efficiency (PCE) of 19.38 %, the highest of the new materials. Although these efficiencies are slightly lower than the benchmark PTAA (20.20 %), the study underscores the potential of iminodibenzyl to enhance photostability and increase HOMO levels, making it a promising candidate for future HTM development in PSCs.

Dopants in hybrid perovskite significantly influence the photovoltaic properties of air-processed perovskite solar cells (a-p PSCs). Chlorine (Cl) is a doping element that substantially increases the crystal and grain sizes and modifies surface morphology as well as perovskite thin films. However, the effect of methylammonium chloride (MACl) as a doping agent has not been systematically studied over a notable range of concentrations. In this study, Cl wt% (or MAClmol) in perovskite precursor solutions (MAI + PbI2) has been varied from 0 to 20 wt% (or MAClfrom 0 to 0.324 mol). It is found that the perovskite thin films prepared from stoichiometric precursor solutions under an air ambient with 0 or 0.023 mol of MACl contain PbI2 impurity, probably due to the loss of MA+ ions during thermal annealing and/or to the moisture attachment on perovskite compounds. This causes a lower photocurrent density at short circuit (JSC) and poorer conversion efficiency (PCE) of the corresponding a-p PSCs. The addition of MACl helps to reduce PbI2 content and increase perovskite crystal and grain sizes as well. However, an excess amount of MACl leads to a rough and porous surface of perovskite with methylammonium species that deteriorate the photovoltaic performance and stability of a-p PSCs. With an optimal concentration of MACl around like 5 wt% (or 0.107 mol), unencapsulated a-p PSCs can hold their original PCE of 18.1 % after a continuous illumination for 30 min under ambient conditions. The enhanced stability of air-processed perovskite thin films should come from the presence of a more electronegative chlorine compared to moisture.

In this work we explore the use of the method of oxidation and heterocyclization of naphthalene diimides (NDIs) to obtain five novel isoquinoline diimide derivatives (IQDI 3-7) as new small molecule acceptors. These derivatives comprise a main core based on triphenylamine (TPA) as electron-donor linked to an isoquinoline diimide moiety as a new electron-acceptor (IQDI 3). The effect on the electronic properties of a further functionalization on TPA achieving A-D-A architectures with additional electron acceptors moieties such as carbonyl group (IQDI 4), 3-methylrhodanine (IQDI 5), 1,3-indandione (IQDI 6) and malononitrile (IQDI 7) was studied. Their electrochemical and optoelectronic properties as well as their performance in photovoltaic devices using J52 as electron-donor polymer were studied being IQDI 6 the compound that showed the best PCE % value.

Emerging photovoltaics for outer space applications are one of the many examples where radiation hard molecular semiconductors are essential. However, due to a lack of general design principles, their resilience against extra-terrestrial high-energy radiation can currently not be predicted. In this work, the discovery of radiation hard materials is accelerated by combining the strengths of high-throughput, lab automation and machine learning. This way, a large material library of more than 130 organic hole transport materials is automatically processed, degraded, and measured. The materials are degraded under ultraviolet-C (UVC) light in a nitrogen atmosphere, serving as the conditions for electromagnetic radiation hardness tests. A value closely related to the differential quantum yield for photodegradation is extracted from the evolution of the UV-visible (UV-vis) spectra over time and used as a stability target. Following this procedure, a stability ranking spanning over 3 orders of magnitude was obtained. Combining Gaussian Process Regression based on predictors from structural fingerprints and manual filtering of the materials by features, structure-stability relations for UVC stable materials could be found: Fused aromatic ring clusters are beneficial, whereas thiophene, methoxy and vinylene groups are detrimental. Comparing the UV-vis spectra of the degraded material in film and solution, bond cleavage could be made out as the leading degradation mechanism. Even though UVC light can in principle break most organic bonds, the stable materials are able to distribute and dissipate the energy well enough so that the chemical structures remain stable. The established predictive model quantifies the effect of specific molecular features on UVC stability, allowing chemists to consider UVC stability in their molecular design strategy. In the future, a larger data set will allow to inversely design molecular semiconductors which show high performance and radiation hardness at the same time.

Perovskite solar cells (PSCs) have become a research hotspot since their dramatic increase in power conversion efficiency (PCE), surpassing 26% due to advances in cell engineering and interfacial layers. Within the last factor, hole transporting materials play a crucial role in enhancing device performance and stability. Among several molecular building blocks, BODIPYs are attractive for the design of novel hole transporting material (HTMs) due to their outstanding photophysical and charge transport properties easily tuned by synthetic modifications. Herein, the synthesis of five new BODIPY‐based HTMs PyBDP 1–5 are reported, functionalized at the meso‐ and α‐ positions with pyrenyl and arylamino units, respectively. The resulting compounds exhibit broad absorption in the visible region, remarkable thermal stability, narrow bandgaps, suitable energy levels, and good hole extraction capability, as subtracted from experimental and computational characterizations. The performance of the BODIPY derivatives as HTMs is evaluated in planar inverted (p‐ i ‐n) PSCs and compared to commonly used PTAA, resulting in highly efficient systems, reaching PCEs very close to that obtained with the reference polymer (21.51%). The incorporation of these BODIPY‐based HTMs result in an outstanding PCE of 20.37% for devices including PyBDP‐1 and 19.97% for devises containing PyBDP‐3 , thus demonstrating that BODIPY derivatives are a promising alternative to obtain simple and efficient organic HTMs.

Objectives: The demographic disparities among surgeons in academic leadership positions is well documented. We aimed to characterize the present demographic details of abdominal transplant surgeons who have achieved academic and clinical leadership positions. Materials and Methods: We reviewed the 2022-2023 American Society of Transplant Surgeons membership registry to identify 1007 active abdominal transplant surgeons. Demographic details (academic and clinical titles) were collected and analyzed using the chi-square test, the Fisher exact test, and t tests. Multinomial logistic regressions were conducted. Results: Female surgeons ( P < .001) and surgeons from racial -ethnic minorities ( P = .027) were more likely to be assistants or associates rather than full professors. White male surgeons were more likely to be full professors than were White female ( P < .001), Asian female ( P = .008), and Asian male surgeons ( P = .005). There were no Black female surgeons who were full professors. The frequency of full professorship increased with surgeon age ( P < .001). Male surgeons were more likely to hold no academic titles ( P < .001). Female surgeons were less likely to be chief of transplant ( P = .025), chief of liver transplant ( P = .001), chief of pancreas transplant ( P = .037), or chair of surgery ( P = .087, significance at 10%). Chief of kidney transplant was the most common clinical position held by a surgeon from a racial or ethnic minority group. Female surgeons were more likely to hold no clinical titles ( P = .001). Conclusions: The underrepresentation of women and people from racial and ethnic minority groups in academic and clinical leadership positions in the field of abdominal transplant surgery remains evident. White male physicians are more likely to obtain full professorship, and they comprise most of the clinical leadership positions overall. A continued push for representative leadership is needed.

A tailored design of asymmetric hole-transporting materials (HTMs) is reported with the synthesis of a family of new HTMs based on the use of the 5 H -dithieno[3,2- b :2′,3′- d ]pyran (DTP) moiety endowed with donor p -methoxytriphenylamines.

The morphology of the active layer in organic solar cells is fundamental for achieving high power conversion efficiency. However, the morphological characteristics for optimal performance are still being investigated. An atomistic computational approach is required to determine the relationship between active layer morphology and performance. Since the organic solar cell has multiple phases and interfaces, the computational modeling of charge generation and transport is challenging. We then used a set of push–pull semiconductors to illustrate how the electronic transmission spectrum, derived from the Landauer–Büttiker formalism, can be used to investigate the efficiency of coherent charge transport across anisotropic organic solids. The electronic transmission spectrum was calculated from the electronic band structure obtained using the density-functional-based tight-binding method. We found that coherent charge transport was more efficient along the direction parallel with the interface between the electron-acceptor and electron-donor moieties for a herringbone morphology.

Eight novel C60-BODIPY-Triarylamine electroactive triads have been synthesized and characterized. Using pyrrolidine (PIR and BDPF series) and isoxazoline (ISO series) as linkers between the fullerene and the BODIPY-Triarylamine (-TAA) system, the effect of these linkers along with different functionalization on the TAA on the electronic properties were studied. Moreover, their photophysical and electrochemical properties were investigated by comparing them to the reference substances BDP, 10a, 10b, and C60. All C60-BODIPY-TAA derivatives absorb visible light strongly in a range between 535 and 563 nm, and photoexcitation of the BODIPY unit causes photo-induced electron transfer, producing the corresponding charge-separated species, which was confirmed by solvatochromic effects on fluorescence measurements. The direction of charge transfer was also revealed by their redox potentials. A better electron affinity was observed for the ISO series when compared with PIR and BDPF. Thermogravimetric analysis showed that the pyrrolidine derivatives are more stable than their isoxazoline analogs and the insertion of alkoxy units in the triads triggers a better thermal endurance in the studied compounds.

Introduction Previous publications have assessed the diversity among medical students, residents, faculty, and department leaders in surgery and medicine overall. We aim to evaluate the diversity among medical school deans in the United States. We quantify and compare the representation of women and underrepresented minority surgeon and non-surgeons. Methods 151 allopathic medical schools were included. Data regarding demographics, education, training, and previous leadership position were collected from institutional websites, online resources, and July 2021 Association of American Medical Colleges Council of Deans. Demographics for surgeon and non-surgeon were compared using chi square and logistic regression with 5% significance interval. Results 21.9% (n = 33) of all medical school deans were surgeons. 21.2% (n = 7) were women, which was not significantly different from non-surgeons (22%, P = .92). All the women surgeons were non-Hispanic white, similar to all deans (P = .83). 78.8% (n = 26) of all surgeon deans were non-Hispanic White compared to 84.7% (n = 100) overall (P = .28). There were 13 Black deans, four of whom were surgeons, and only one Hispanic dean, who was not a surgeon. Surgeons were more likely to be fellows of their professional society (P = .012). Conclusion The demographic diversity of surgeon and non-surgeon US medical school deans is not significantly different. The deficiencies in leadership diversity in medicine persists among medical school deans. There remains substantial room to improve the representation of women and underrepresented minorities as deans.

Dumbbell‐shaped systems based on PAHs‐BODIPY‐triarylamine hybrids TM‐(01‐04) are designed as novel and highly efficient hole‐transporting materials for usage in planar inverted perovskite solar cells. BODIPY is employed as a bridge between the PAH units, and the effects of the conjugated π ‐system's covalent attachment and size are investigated. Fluorescence quenching, 3D fluorescence heat maps, and theoretical studies support energy transfer within the moieties. The systems are extremely resistant to UVC 254 nm germicidal light sources and present remarkable thermal stability at degradation temperatures exceeding 350 °C. Integrating these systems into perovskite solar cells results in outstanding power conversion efficiency (PCE), with TM‐02‐based devices exhibiting a PCE of 20.26%. The devices base on TM‐01, TM‐03, and TM‐04 achieve PCE values of 16.98%, 17.58%, and 18.80%, respectively. The long‐term stability of these devices is measured for 600 h, with initial efficiency retention between 94% and 86%. The TM‐04‐based device presents noticeable stability of 94%, better than the reference polymer PTAA with 91%. These findings highlight the exciting potential of dumbbell‐shaped systems based on PAHs‐BODIPY‐triarylamine derivatives for next‐generation photovoltaics.

In this work, we present the synthesis of novel D-pi-A compounds based on the structure of 2-(3-hexyl-2-oxoimidazolin-4-ylidene) malononitrile, which can function as an acceptor group and anchoring group to the TiO2 surface. The synthetic route of the dyes involving a Knoevenagel condensation under microwave irradiation with donors based on triphenylamine (TPA) and thiophene moiety as a conjugated wire. Additionally, absorption, emission and electrochemical experiments were carried out to demonstrate a push-pull behavior in all the dyes. Finally, DCH 1-6 dyes were tested as photosensitizers in Gratzel type solar cells showing a low PCE values (between 0.10% and 0.60%), due to the poor electron injection on TiO2 surface for the low LUMO energy levels of the prepared dyes. (C) 2021 Elsevier B.V. All rights reserved.

OBJECTIVES:The diversity in the governance of the American Society of Transplant Surgeons has not been described. We aimed to quantify the present state of its leadership as a baseline to inform future research.MATERIALS AND METHODS:Lists of leaders on the American Society of Transplant Surgeons Council, the COVID-19 Strike Force, and 20 different American Society of Transplant Surgeons committees were obtained from the Society's website. Demographic and training information for the members were compiled through internet searches and analyzed.RESULTS:The American Society of Transplant Surgeons Council included 15 members, with 20% women. It was 93.3% non-Hispanic White. The COVID-19 Strike Force included 12 surgeons, 16.7% of whom were female, with 75% non-Hispanic White. Of the 198 committee members, 23.7% were women, 68.7% were nonHispanic White, 16.6% were Asian, 8.1% were Hispanic, and 6.6% were Black. Among female committee members, underrepresented minorities comprised 23.6%. Committee chairs included 23% women, 23% underrepresented minorities, and 2.3% minority women. International medical graduates were more likely men (P = .02).CONCLUSIONS:Representation of women in the American Society of Transplant Surgeons leadership has kept pace with their membership in the transplant surgery workforce. There is a deficiency of female under - represented minorities in leadership positions at the Society. Further interventions are required to recruit underrepresented minorities to transplant surgery, catalog their footprint in the workforce, and champion their role as leaders within the American Society of Transplant Surgeons.

Two novel and simple donor-π-bridge-donor (D-π-D) hole-transporting materials (HTMs) containing two units of the p-methoxytriphenylamine (TPA) electron donor group covalently bridged by means of the 3,4-dimethoxyselenophene spacer through single and triple bonds are reported. The optoelectronic and thermal properties of the new selenium-containing HTMs have been determined using standard experimental techniques and theoretical density functional theory (DFT) calculations. The selenium-based HTMs have been incorporated in mesoporous perovskite solar cells (PSCs) in combination with the triple-cation perovskite [(FAPbI3 )0.87 (MAPbBr3 )0.13 ]0.92 [CsPbI3 ]0.08 . Limited values of power conversion efficiencies, up to 13.4 %, in comparison with the archetype spiro-OMeTAD (17.8 %), were obtained. The reduced efficiencies showed by the new HTMs are attributed to their poor film-forming ability, which constrains their photovoltaic performance due to the appearance of structural defects (pinholes).

The search for high-efficiency narrow-band donor materials to improve the short-circuit current density (Jsc) of organic solar cells, a series of small molecules based in Bodipy-Triphenylamine were characterized using density functional theory (DFT) and time-dependent (TD-DFT) calculations. According to the energy of the exciton driving force they have the appropriate energy levels to match PC61BM. The properties affecting the open circuit voltage (Voc), Jsc and the fill factor (FF) were investigated by calculating the geometric structures, the boundary molecular orbital energy levels, absorption spectra, light collection efficiencies, charge transfer rates, and exciton binding energies. The results show that the BTPA III system has a lower LUMO level, high absorption efficiency, and exciton dissociation than other molecular systems, facilitating the improvement of Voc,Jsc and FF. Finally, BTPA III would be the most promising of this series of donors and further increase the efficiency of the device.