Effect of organic and inorganic passivation in quantum-dot-sensitized solar cells

The effect of semiconductor passivation on quantum-dot-sensitized solar cells (QDSCs) has been systematically characterized for CdS and CdS/ZnS. We have found that passivation strongly depends on the passivation agent, obtaining an enhancement of the solar cell efficiency for compounds containing amine and thiol groups and, in contrast, a decrease in performance for passivating agents with acid groups. Passivation can induce a change in the position of TiO2 conduction band and also in the recombination rate and nature, reflected in a change in the β parameter. Especially interesting is the finding that β, and consequently the fill factor can be increased with the passivation treatment. Applying this strategy, record cells of 4.65% efficiency for PbS-based QDSCs have been produced.This work was supported by the Institute of Nanotechnologies for Clean Energies (INCE), funded by the Generalitat Valenciana under Project ISIC/2012/008. We thank the following agencies for support of this research: Ministerio de Educacion y Ciencia under project HOPE CSD2007-00007, Generalitat Valenciana (ISIC/2012/008), and Universitat Jaume I project 12I361.01/1. We acknowledge projects CYTED-Nanoenergía, PAPIIT-IN106912 (UNAM-México), and CONACyT-153270 (México) for financial support. M.S.F. acknowledges the fellowship given by CONACyT-México. Funding from National Research Foundation (NRF) Singapore is also kindly acknowledged (CRP Award No. NRF-CRP4-2008-03)

Intraperitoneal drain placement and outcomes after elective colorectal surgery: international matched, prospective, cohort study

Despite current guidelines, intraperitoneal drain placement after elective colorectal surgery remains widespread. Drains were not associated with earlier detection of intraperitoneal collections, but were associated with prolonged hospital stay and increased risk of surgical-site infections.Background Many surgeons routinely place intraperitoneal drains after elective colorectal surgery. However, enhanced recovery after surgery guidelines recommend against their routine use owing to a lack of clear clinical benefit. This study aimed to describe international variation in intraperitoneal drain placement and the safety of this practice. Methods COMPASS (COMPlicAted intra-abdominal collectionS after colorectal Surgery) was a prospective, international, cohort study which enrolled consecutive adults undergoing elective colorectal surgery (February to March 2020). The primary outcome was the rate of intraperitoneal drain placement. Secondary outcomes included: rate and time to diagnosis of postoperative intraperitoneal collections; rate of surgical site infections (SSIs); time to discharge; and 30-day major postoperative complications (Clavien-Dindo grade at least III). After propensity score matching, multivariable logistic regression and Cox proportional hazards regression were used to estimate the independent association of the secondary outcomes with drain placement. Results Overall, 1805 patients from 22 countries were included (798 women, 44.2 per cent; median age 67.0 years). The drain insertion rate was 51.9 per cent (937 patients). After matching, drains were not associated with reduced rates (odds ratio (OR) 1.33, 95 per cent c.i. 0.79 to 2.23; P = 0.287) or earlier detection (hazard ratio (HR) 0.87, 0.33 to 2.31; P = 0.780) of collections. Although not associated with worse major postoperative complications (OR 1.09, 0.68 to 1.75; P = 0.709), drains were associated with delayed hospital discharge (HR 0.58, 0.52 to 0.66; P < 0.001) and an increased risk of SSIs (OR 2.47, 1.50 to 4.05; P < 0.001). Conclusion Intraperitoneal drain placement after elective colorectal surgery is not associated with earlier detection of postoperative collections, but prolongs hospital stay and increases SSI risk

Solution-processed n-type organic field-effect transistors with high ON/OFF current ratios based on fullerene derivatives

Solution-processed n-type organic field-effect transistors (OFETs) based on the fullerene derivative {6}-1-(3-(2-thienylethoxycarbonyl)-propyl)-{5}-1-phenyl-[5,6]-C61 (TEPP) and phenyl-C61-butyric acid methyl ester (PCBM) in a multiring source/ drain structure are reported. Devices with TEPP show high electron mobility up to 7.8 × 10cm/Vs in the saturation regime for bottom-contact OFETs with Au S/D electrodes with a solution-processed fullerene derivative. The on/off ratios reported in this letter, which are in the range of 10 - 10, are among the highest values reported for such devices. This mobility is always higher compared to PCBM devices prepared in identical conditions. The mobility of TEPP and PCBM increased with increasing temperatures in the range of 100-300 K with activation energy of 78 and 113 meV, respectively, which suggests that the thermally activated hopping of electrons is dominant in TEPP

Electrically driven incandescence of carbon nanotubes in controlled gaseous environments

10.1016/j.scriptamat.2010.11.044Scripta Materialia646564-567SCMA

Pentacene organic field effect transistors on flexible substrates with polymer dielectrics

Pentacene Organic Field Effect Transistors are fabricated using polymethyl methacrylate (PMMA) as a gate dielectric on flexible polymeric substrates like the Indium tin oxide coated polyethylene terephthalate (ITO coated PET), and polyethylene napthalate (PEN) in top contact configuration. The ITO and aluminium (evaporated on PEN) act as the gate materials for the OFETs. The devices on ITO coated PET show electron mobility up to 0.07 cm/V-s and the on/off ratios in the order of 10

Improving the performance of carbon-based perovskite solar modules (70 cm2) by incorporating cesium halide in mesoporous TiO 2

We present the fabrication of highly efficient large-area carbon-based perovskite solar cells (C-PSCs) using CsX (X = Cl, Br, and I)-modified mesoporous (mp) TiO2 beads of 40 nm size as an electron transport material. Here, triple-layered scaffolds made of cesium halide-modified TiO2 exhibit efficient charge extraction as confirmed by enhanced photoluminescence quenching and inhibit the UV-activated degradation processes of perovskite, leading to an enhanced operational stability. Among the three cesium halide modifications, devices containing CsBr-modified TiO2 showed the highest short-circuit current density, yielding a photoconversion efficiency (PCE) of 12.59% of the device, with 0.7 cm(2) active area and 11.55% for a large-area module (70 cm(2)). These devices are stable in an ambient atmosphere (25 degrees C, 65-70% RH) over 2700 h as well as at a high temperature (85 degrees C) over 750 h with virtually no hysteresis