Novel dopant-free hole-transporting materials for efficient perovskite solar cells
SOLAR ENERGY
Authors: Abdellah, Islam M.; Chowdhury, Towhid H.; Lee, Jae-Joon; Islam, Ashraful; El-Shafei, Ahmed
Abstract
Two novel highly conjugated small organic molecules as hole transporting materials (HTMs) coded T(EDOT-TPA) 2 and DBT(QT-TPA)(2) were designed and developed by utilizing facile synthetic procedures with high yields. The fabricated perovskite solar cells (PSCs) utilizing these HTMs without any dopants under 1 sun illumination (100 mW cm(-2), AM 1.5G) and surface area of 1.02 cm(2) achieved a short circuit current (J(SC) = 19.23), open circuit voltage (V-OC = 1.042), fill factor (FF = 0.679) and overall power conversion efficiency (PCE = 13.61%) for DBT(QT-TPA)(2). While, T(EDOT-TPA)(2) exhibited (J(SC) = 20.25, V-OC = 1.04, FF = 0.583, and PCE = 12.27%). These dopant free HTM based PSCs achieved superior PCEs compared to that of undoped Spiro-OMeTAD (PCE = 9.34%) based PSCs and a comparable photovoltaic performance to the PSCs using doped Spiro-OMeTAD (J(SC) = 20.37, V-OC = 1.057, FF = 0.74, and PCE = 15.93) as the HTM under same fabrication conditions. Noticeably, the absence of additives is of significant importance, as DBT(QT-TPA) 2 and T(EDOT-TPA)(2) based PSCs still produces a J(sc) up to 20.25 mA cm(-2) and a comparable PCE of 13.61%, which reduces the fabrication cost of cm sized PSCs.
An Observational Study Investigating the Need for Decompressive Hemicraniectomy after Thrombectomy in Acute Ischemic Stroke of the Middle Cerebral Artery Territory
CUREUS
Authors: Salehani, Arsalaan; Tabibian, Borna E.; Self, D. M.; Agee, Bonita; Chagoya, Gustavo; Stetler, William; Fisher, Winfield S.
Abstract
Objective: The frequency incidence of decompressive hemicraniectomy following intra-arterial thrombectomy (IAT) in acute ischemic stroke (AIS) involving the middle cerebral artery (MCA) territory was assessed as a surrogate for morbidity. Methods: A single-institution retrospective chart review was conducted involving 209 consecutive patients between September 2014 and May 2017 with infarctions affecting the MCA territory and who subsequently underwent IAT. The outcomes of interest included the frequency of hemicraniectomy following IAT and the effects of intravenous tissue plasminogen activator (IV tPA) use and primary occlusion site on the Thrombolysis in Cerebral Infarction (TICI) score. Results: Thirty-one patients were excluded for infarctions not involving the MCA territory. A total of 178 patients were included in the study. Sixty-eight patients (38.6%) had infarctions of less than one-third of the MCA territory, 50 (28.4%) had infarctions between one-third and two-thirds, and 58 (33%) had infarctions involving greater than two-thirds with 54.3% suffering infarctions of the left side. Only four patients (2.2%) required a hemicraniectomy with no statistically significant association found between TICI score and hemicraniectomy (p=0.41) or between administration of IV tPA and hemicraniectomy (p=0.36). The primary occlusion site was found to influence TICI score (p=0.045). Conclusion: A very small number of patients required hemicraniectomy after IAT as compared to previously published rates in the literature. llowever, several factors may prevent the patient from being an appropriate hemicraniectomy candidate in the first place and the small number of these patients in this study limits statistical analysis. The variables that determine a patient's candidacy for decompressive hemicraniectomy remains multi-factorial.