Highly luminescent double-heterojunction nanorods.

Anisotropic shape and band structure engineered into double-heterojunction nanorods (DHNRs) can improve and impart new optical/optoelectronic capabilities in colloidal quantum dot-based devices. However, the photoluminescence quantum yield of DHNRs, which is significantly lower than the near-ideal limit recently achieved in the state-of-the-art core/shell quantum dots, remains as their main limitation. Here, we examine how the photoluminescence of CdS/CdSe/ZnSe DHNRs is affected by (1) the length of the CdS seed nanorods, (2) the rod and tip diameter dependent variations in band offset, and (3) the CdSe-like islands on the sides of DHNRs that can result as a side-product of ZnSe shell growth. By understanding and optimizing these three key parameters, we demonstrate an improvement in the photoluminescence quantum yield up to 93% (up to 62% for excitation above CdS bandgap) while retaining useful shape anisotropy and the band structure design in DHNRs.

Efficient Type-II Heterojunction Nanorod Sensitized Solar Cells Realized by Controlled Synthesis of Core/Patchy-Shell Structure and CdS Cosensitization.

Here, we report the successful application of core/patchy-shell CdSe/CdSe xTe1- x type-II heterojunction nanorods (HNRs) to realize efficient sensitized solar cells. The core/patchy-shell structure designed to have a large type-II heterointerface without completely shielding the CdSe core significantly improves photovoltaic performance compared to other HNRs with minimal or full-coverage shells. In addition, cosensitization with CdS grown by successive ionic layer adsorption and reaction further improves the power conversion efficiency. One-diode model analysis reveals that the HNRs having exposed CdSe cores and suitably grown CdS result in significant reduction of series resistance. Investigation of the intercorrelation between diode quality parameters, diode saturation current density ( J0) and recombination order (ß = (ideality factor)-1) reveals that HNRs with open CdSe cores exhibit reduced recombination. These results confirm that the superior performance of core/patchy-shell HNRs results from their fine-tuned structure: photocurrent is increased by the large type-II heterointerface and recombination is effectively suppressed due to the open CdSe core enabling facile electron extraction. An optimized power conversion efficiency of 5.47% (5.89% with modified electrode configuration) is reported, which is unmatched among photovoltaics utilizing anisotropic colloidal heterostructures as light-harvesting materials.

Photoresist Contact Patterning of Quantum Dot Films.

Scalable and cost-effective protocols to pattern and integrate colloidal quantum dots (QDs) with high resolution have been challenging to establish. While their solubility can facilitate certain processes such as spin-casting into thin films, it also makes them incompatible with many conventional patterning techniques including photolithography that require solution processing. In this work, we present "photoresist (PR) contact patterning", a dry means to pattern QD films over large areas with high resolution while maintaining desired properties. Here, a PR layer on an elastomer substrate is patterned by conventional photolithography and used as a dry contact stamp to selectively peel off QDs in the contact regions, leaving behind a QD film with the negative of the PR pattern. Once patterned, QD films are readily transferred and integrated on foreign substrates by subsequent transfer printing processes. Patterned PR layers can also be transferred from elastomer substrates onto QD films and used as masking layers for subsequent deposition and patterning of additional materials, e. g., patterned metal electrodes or charge transport layers for QD-based devices. The study of the interfacial mechanics and energy of materials associated with PR contact patterning reveals why a lithographically patterned PR is superior for high-resolution QD film patterning. Applicability of PR contact patterning is demonstrated through the fabrication of red, green, and blue (RGB) QD light-emitting diode pixels. PR contact patterning presented in this work not only allows dry patterning of QD films but also enables high-resolution integration of functional multistack structures for future QD-based electronic and optoelectronic devices.

Route to Improving Photovoltaics Based on CdSe/CdSexTe1-x Type-II Heterojunction Nanorods: The Effect of Morphology and Cosensitization on Carrier Recombination and Transport.

One-dimensionally elongated nanoparticles with type-II staggered band offset are of potential use as light-harvesting materials for photovoltaics, but only a limited attention has been given to elucidate the factors governing the cell performance obtainable from such materials. Herein, we describe a combined strategy to enhance charge collection from CdSe/CdSexTe1-x type-II heterojunction nanorods (HNRs) utilized as light harvesters for sensitized solar cells. By integrating morphology- and composition-tuned type-II HNRs into solar cells, factors that yield interfaces favorable both for the electron injection into TiO2 and hole transfer to electrolyte are examined. Furthermore, it is shown that a more efficient photovoltaic system results from cosensitization with CdS quantum dots (QDs) predeposited on a TiO2 scaffold, which improves charge collection from HNRs. Electrochemical impedance spectroscopy (EIS) analysis suggests that such a synergistically enhanced system benefits from the decreased recombination within HNRs and facilitated charge transport through the cosensitized TiO2 electrode, even with the activation of a recombination path presumably related to the photogenerated holes in CdS QDs.

Double-heterojunction nanorod light-responsive LEDs for display applications.

Dual-functioning displays, which can simultaneously transmit and receive information and energy through visible light, would enable enhanced user interfaces and device-to-device interactivity. We demonstrate that double heterojunctions designed into colloidal semiconductor nanorods allow both efficient photocurrent generation through a photovoltaic response and electroluminescence within a single device. These dual-functioning, all-solution-processed double-heterojunction nanorod light-responsive light-emitting diodes open feasible routes to a variety of advanced applications, from touchless interactive screens to energy harvesting and scavenging displays and massively parallel display-to-display data communication.

Integration of CdSe/CdSexTe1-x Type-II Heterojunction Nanorods into Hierarchically Porous TiO2 Electrode for Efficient Solar Energy Conversion.

Semiconductor sensitized solar cells, a promising candidate for next-generation photovoltaics, have seen notable progress using 0-D quantum dots as light harvesting materials. Integration of higher-dimensional nanostructures and their multi-composition variants into sensitized solar cells is, however, still not fully investigated despite their unique features potentially beneficial for improving performance. Herein, CdSe/CdSe(x)Te(1-x) type-II heterojunction nanorods are utilized as novel light harvesters for sensitized solar cells for the first time. The CdSe/CdSe(x)Te(1-x) heterojunction-nanorod sensitized solar cell exhibits ~33% improvement in the power conversion efficiency compared to its single-component counterpart, resulting from superior optoelectronic properties of the type-II heterostructure and 1-octanethiol ligands aiding facile electron extraction at the heterojunction nanorod-TiO(2) interface. Additional ~31% enhancement in power conversion efficiency is achieved by introducing percolation channels of large pores in the mesoporous TiO(2) electrode, which allow 1-D sensitizers to infiltrate the entire depth of electrode. These strategies combined together lead to 3.02% power conversion efficiency, which is one of the highest values among sensitized solar cells utilizing 1-D nanostructures as sensitizer materials.

Allergic fungal sinusitis involving the lacrimal sac: a case report and review.

UNLABELLED: BACKGROUNd: We report a case of allergic fungal sinusitis (AFS) involving the lacrimal sac and review the current English literature. A literature search for AFS involving the lacrimal sac revealed two reports with only one of the two cases demonstrating histological evidence of fungal elements. This is just the third such case and only the second reported case with histopathologic confirmation of fungal elements by Gomori methenamine silver (GMS) stain. MATERIALS AND METHODS: A PubMed database search was performed using combinations of the following key words: allergic fungal sinusitis, lacrimal sac, nasolacrimal duct, ophthalmology, epiphora, orbit. A 70-year-old white man with a history of chronic conjunctivitis and nasal polyps presenting with chronic epiphora was found to have dacryostenosis on the left side. A CT scan of the orbits revealed mucoperiosteal thickening completely obliterating the frontal, ethmoid and sphenoid sinuses. RESULTS: A left external dacryocystorhinostomy (DCR) was performed and the lacrimal sac contents were studied histopathologically. Microscopic examination of the lacrimal sac contents disclosed allergic mucin with laminated aggregates of eosinophils in various stages of degeneration, Charcot-Leyden crystals and rare noninvasive fungal hyphae confirming the diagnosis of AFS. Fungal elements stained positively with Gomori methenamine silver stain. CONCLUSION: Although rarely reported, AFS can affect the lacrimal sac. AFS should be suspected in patients with a history of recurrent refractory sinusitis, recurrent dacryocystitis and nasal polyposis. Early diagnosis is important for adequate treatment and prevention of recurrence.

Postoperative eyelid infection in a patient taking etanercept.

Postoperative eyelid infections are a rare complication of eyelid surgery. The authors present a case of an eyelid infection occurring within the first week following surgery in a patient taking etanercept--a biologic anti-TNF-α agent used in the treatment of rheumatoid arthritis. The authors urge caution regarding the use of steroid/antibiotic combination ointments and systemic steroids in patients undergoing elective eyelid surgery who are on such medications. Perioperative discontinuation of etanercept in consultation with the prescribing physician may also be considered. Eyelid infections following eyelid surgeries such as blepharoplasty and ptosis correction are uncommon.( 1 , 2 ) A review of a large series of blepharoplasty procedures estimated the rate of postoperative infection at 0.2%.( 3 ) However, patients who are relatively immunosuppressed may be at a higher risk of developing skin and eyelid infections. We present a case of postoperative infection in a patient who was taking etanercept (Enbrel, Immunex Corporation, Thousand Oaks, CA) for rheumatoid arthritis.

Dacryocystorhinostomy: History, evolution and future directions.

Dacryocystorhinostomy (DCR) is a procedure of choice for nasolacrimal duct obstruction and chronic dacryostenosis in the setting of patent canaliculi and a functional lacrimal pump. Two major approaches are utilized: external, via a transcutaneous incision and endonasal endoscopically guided. The surgery has a high success rate via both approaches. We review the history, evolution, current techniques, complications and future directions of DCR.

Palpebral subconjunctival hemorrhages in herpes zoster ophthalmicus.

A 75-year-old previously healthy woman was referred for evaluation of pain and foreign body sensation in her left eye of 4 days' duration. Two weeks before presentation she was diagnosed with herpes zoster involving the left forehead and temple area and started on famciclovir treatment. Examination of her left cornea revealed inferior superficial punctate keratitis, but no dendrites or pseudodendrites. Upper eyelid eversion disclosed unusual raised palpebral subconjunctival hemorrhages on the left side. She was started on topical prednisolone eyedrops in the left eye, and her symptoms improved over the following week. Herpes zoster ophthalmicus can initially present in the eyelids. Careful follow-up with particular attention to the eyelids and eyelid eversion is recommended in any patient presenting with herpes zoster to detect early ocular involvement.

Incidence of postblepharoplasty orbital hemorrhage and associated visual loss.

PURPOSE: Orbital hemorrhage, especially when associated with visual loss, is a significant complication of cosmetic eyelid surgery. We investigated the incidence of this complication among cases handled by members of the American Society of Ophthalmic Plastic and Reconstructive Surgery. We also reviewed the length of time between surgery and the onset of bleeding and sought any factors that may contribute to these cases. METHODS: A 2-page questionnaire was sent to all American Society of Ophthalmic Plastic and Reconstructive Surgery members. Responses were tabulated as to total numbers of cases performed, the incidence of postoperative orbital hemorrhage, treatments, and incidence of permanent visual loss. Comorbidities were also reviewed. RESULTS: Two hundred thirty-seven responses were received from American Society of Ophthalmic Plastic and Reconstructive Surgery members, collectively representing 269,433 cases. Among these cases, there were 149 orbital hemorrhages, 48 cases associated with temporary visual loss, and 12 cases associated with permanent visual loss. The majority of these cases occurred within the first 3 hours of surgery, and the risk decreased significantly after 24 hours after surgery. Common comorbidities were hypertension, perioperative aspirin use, postoperative vomiting, and increased physical activity. Treatment commonly consisted of wound drainage with cauterization of active bleeders, lateral canthotomy, intravenous steroids, and intraocular pressure-lowering drugs. Orbital decompression was infrequently used; anterior chamber paracentesis was not used. This study is limited by recall biases regarding the number of cases performed by each responding surgeon and the number of relevant cases of orbital hemorrhage. CONCLUSIONS: The incidence of orbital hemorrhage associated with cosmetic eyelid surgery is 0.055% (1:2,000), and orbital hemorrhage with permanent visual loss is 0.0045% (1:22,000) [corrected] Development of orbital hemorrhage is most common within the first 24 hours after surgery, especially within the first 0 to 3 hours, but can occur as late as several days after surgery.

Ocular surface, ocular adnexal, and lacrimal complications associated with the use of systemic 5-fluorouracil.

PURPOSE: To determine the prevalence rates and associated characteristics of patients who have ocular surface, ocular adnexal, and lacrimal complications associated with the systemic use of the cancer chemotherapeutic agent 5-Fluorouracil (5-FU). METHODS: An exposure-based cohort study was designed. Adult patients who had completed at least 3 months of systemic 5-FU therapy within the past 5 years were eligible for enrollment. Study subjects had a detailed medical history taken with emphasis on preexisting conditions known to be associated with the development of ocular surface, ocular adnexal, and lacrimal complications. An ocular examination was then performed. A complete nasolacrimal system evaluation was performed if symptoms or findings were identified. The prevalence was then determined for each ocular symptom and each ocular finding identified that was not present pretreatment. An exploratory analysis was then performed to identify patient characteristics that might influence the likelihood of developing any of the above complications. RESULTS: Fifty-two patients were enrolled in the study. The prevalence rates of the following ocular abnormalities were calculated: ocular irritation, 5.8%; blepharitis, 3.8%; conjunctivitis, 3.8%; keratitis, 3.8%; eyelid dermatitis, 5.8%; cicatricial ectropion, 1.9%; tearing, 26.9%; punctal-canalicular stenosis, 5.8%; and blurred vision, 11.5%. Blacks had tearing at a significantly higher rate when compared with whites (P = 0.022, 2-sided Fisher exact test). Three patients had permanent complications that will require surgery for correction. Of the 7 patients who had a single abnormality, 6 had tearing and one had eyelid dermatitis. All of the 8 patients who had multiple findings had tearing as one of their abnormalities. CONCLUSIONS: Ninety-three percent of the patients who had an ocular abnormality had tearing as one of the complications. Patients who are receiving systemic 5-FU and begin to tear should have an ocular examination, looking for ocular surface, ocular adnexal, and lacrimal complications.