An investigation of the role the donor moiety plays in modulating the efficiency of ‘donor-π-acceptor-π-acceptor’ organic DSSCs

Three ‘D-π-A-π-A’ based dyes have been synthesized featuring MeO-, MeS- and Me2N- as donor residues and benzothiadiazole and cyanoacrylic acid residues as acceptor units. UV–vis spectroscopy, solution electrochemistry and DFT modelling indicated that the Me2N- residue has the most significant effect on optical and redox properties of a photosensitizer. DSSCs with the Me2N- functionalized dye gave the highest power conversion efficiency of the series (η = 5.61%), presumably due to the better donor ability of this unit, which promotes more effective intramolecular charge transfer (ICT) characteristics

Customized Energy Down-Shift using Iridium Complexes for Enhanced Performance of Polymer Solar Cells

School of Molecular Sciences(Chemistry)For the higher performance of polymer solar cells (PSCs), many researchers tried to develop new polymers that can absorb broader range of spectrum. However, there are some limits to absorb broader range with single donor. Therefore, multi donor systems and energy transfer systems have been researched. With two different donors it is easier to enhance absorption range. As a result, multi donor and energy transfer was successful to increase performance. However, the existing systems are applying polymer-polymer systems. When two different polymers are mixed, the compatibility between two polymers is critical to morphology of blend film. Also, in polymer-polymer energy transfer, the boundary between charge transfer and energy transfer is unclear. Therefore, for the first time, we developed customized iridium (Ir(III)) complexes, with Ir(III) complex incorporated into the active materials poly(thieno[3,4-b]-thiophene/benzodithiophene) (PTB7, amorphous) or poly(3-hexylthiophene) (P3HT, high crystalline) as energy donor additives. The Ir(III) complex with the 2-phenyl quinolone ligand energy donor increased the power conversion efficiency of the corresponding devices by approximately 20%. The enhancements are attributed to the improved molecular compatibility and energy level between the Ir(III) complex and the active materials, long F??rster resonance energy transfer radius, and high energy down-shift efficiency. Overall, we reveal Ir(III) complex additives for amorphous and highly crystalline polymer active materialsthese additives would enable efficient energy transfer in polymer solar cells, while retaining the desirable active layer morphology, thereby resulting in improved light absorption and conversion.ope

Clinical Review of Endogenous Endophthalmitis in Korea: A 14-Year Review of Culture Positive Cases of Two Large Hospitals

PURPOSE: To identify the clinical features and outcomes of endogenous endophthalmitis in Korea. MATERIALS AND METHODS: We reviewed 18 patients with endogenous endophthalmitis at 2 Korean hospitals, treated over a 14 year period between January 1993 and December 2006. RESULTS: The comorbidities observed in these cases were diabetes mellitus and liver cirrhosis. The most common pathogens, which were found in 7 patients each (38.9%), were Klebsiella pneumonia and Pseudomonas aeruginosa. All patients were treated with systemic antibiotics and fortified topical antibiotics. A surgical approach including vitrectomy was performed in 9 cases (50.0%). The prognosis was generally poor, and visual acuity improved slightly in 6 patients (33.3%). CONCLUSION: In this study, diabetes mellitus and Klebsiella pneumonia showed a close relationship with endogenous endophthalmitis, respectively. Endogenous endophthalmitis is a serious risk to sight and careful attention to establishing the diagnosis and management may decrease the ocular morbidity.ope

Stretchable and recoverable acrylate-based pressure sensitive adhesives with high adhesion performance, optical clarity, and metal corrosion resistance

In the era of the Internet of Things, digital displays play a critical role in human-machine interfaces. In particular, displays applied to contemporary devices such as flexible smart watches and foldable/rollable electronics underline the need for pertinent materials and device technologies to fulfill their designed functions. However, despite the technical advancements of electronic components such as stretchable/flexible electrodes and flexible backplanes, their proper assembly remains a challenge. Herein, we report the compositional effect of acrylic acid (AA) on the physical properties of as-synthesized pressure sensitive adhesives (PSAs), especially on their adhesion performance in terms of wettability and peel adhesion. Accordingly, an empirical criterion for intimate wetting is proposed based on the storage modulus of the PSAs. In this study, the PSA with the best adhesion performance was evaluated for its viscoelastic properties and suitability for specific applications. The results demonstrated the strain-dependent conformational recovery of the adhesive; the implementation of the prestrain strategy enables rapid strain reversibility at 25% of the total strain. Furthermore, the AA-incorporated PSAs exhibited remarkable metal corrosion resistance as well as high optical clarity. Thus, this fundamental study of stretchable PSAs can provide useful guidance for the development of advanced PSAs that can be used in a wide range of applications involving display devices

Clinical Features of Re-Emerging Hepatitis A: An Analysis of Patients Hospitalized during an Urban Epidemic in Korea

From April 2008 to November 2008, many cases of hepatitis A were reported in Seoul and Gyeonggi Province in Korea. Furthermore, the rate of severe or fulminant hepatitis have significantly increased during the latest epidemic (13.4% vs. 5.2%, p=0.044). Therefore, widespread use of vaccine is warranted to reduce the burden of hepatitis A in Korea