Expression of concern: Tin-zinc-oxide nanocomposites (SZO) as promising electron transport layers for efficient and stable perovskite solar cells.

Expression of concern for 'Tin-zinc-oxide nanocomposites (SZO) as promising electron transport layers for efficient and stable perovskite solar cells' by Ahmed E. Shalan et al., Nanoscale Adv., 2019, 1, 2654-2662, DOI: https://doi.org/10.1039/C9NA00182D.

Expression of Concern: Concordantly fabricated heterojunction ZnO-TiO2 nanocomposite electrodes via a co-precipitation method for efficient stable quasi-solid-state dye-sensitized solar cells.

Expression of concern for 'Concordantly fabricated heterojunction ZnO-TiO2 nanocomposite electrodes via a co-precipitation method for efficient stable quasi-solid-state dye-sensitized solar cells' by Ahmed Esmail Shalan et al., RSC Adv., 2015, 5, 103095-103104, DOI: 10.1039/C5RA21822E.

Correction: Controlling barrier height and spectral responsivity of p-i-n based GeSn photodetectors via arsenic incorporation.

[This corrects the article DOI: 10.1039/D3RA00805C.].

Controlling barrier height and spectral responsivity of p-i-n based GeSn photodetectors via arsenic incorporation.

GeSn compounds have made many interesting contributions in photodetectors (PDs) over the last ten years, as they have a detection limit in the NIR and mid-IR region. Sn incorporation in Ge alters the cut off wavelength. In the present article, p-i-n structures based on GeSn junctions were fabricated to serve as PDs. Arsine (As) is incorporated to develop n-GeSn compounds via a metal induced crystallization (MIC) process followed by i-GeSn on p-Si wafers. The impact of As and Sn doping on the strain characteristics of GeSn has been studied with high resolution transmission electron microscopy (HRTEM), X-ray diffraction and Raman spectroscopy analyses. The direct transitions and tuning of their band energies have been investigated using diffuse reflectance UV-vis spectroscopy and photoluminescence (PL). The barrier height and spectral responsivity have been controlled with incorporation of As. Variation of As incorporation into GeSn Compounds shifted the Raman peak and hence affected the strain in the Ge network. UV-vis spectroscopy showed that the direct transition energies are lowered as the Ge-As bonding increases as illustrated in Raman spectroscopy investigations. PL and UV-vis spectroscopy of annealed heterostructures at 500 °C showed that there are many transition peaks from the UV to the NIR region as result of oxygen vacancies in the Ge network. The calculated diode parameters showed that As incorporation leads to an increase of the height barrier and thus dark current. Spectral response measurements show that the prepared heterojunctions have spectral responses in near UV and NIR regions that gives them opportunities in UV and NIR photodetection-applications.

A Robust and Highly Precise Alternative against the Proliferation of Intestinal Carcinoma and Human Hepatocellular Carcinoma Cells Based on Lanthanum Strontium Manganite Nanoparticles.

In this report, lanthanum strontium manganite at different Sr2+ ion concentrations, as well as Gd3+ or Sm3+ ion substituted La0.5-YMYSr0.5MnO3 (M = Gd and Sm, y = 0.2), have been purposefully tailored using a sol gel auto-combustion approach. XRD profiles confirmed the formation of a monoclinic perovskite phase. FE-SEM analysis displayed a spherical-like structure of the La0.8Sr0.2MnO3 and La0.3Gd0.2Sr0.2MnO3 samples. The particle size of the LSM samples was found to decrease with increased Sr2+ ion concentration. For the first time, different LSM concentrations were inspected for their cytotoxic activity against CACO-2 (intestinal carcinoma cells) and HepG-2 (human hepatocellular carcinoma cells). The cell viability for CACO-2 and HepG-2 was assayed and seen to decrease depending on the Sr2+ ion concentration. Half maximal inhibitory concentration IC50 of CACO-2 cell and HepG-2 cell inhibition was connected with Sr2+ ion ratio. Low IC50 was noticable at low Sr2+ ion content. Such results were correlated to the particle size and the morphology. Indeed, the IC50 of CACO-2 cell inhibition by LSM at a strontium content of 0.2 was 5.63 ± 0.42 µg/mL, and the value increased with increased Sr2+ ion concentration by up to 0.8 to be = 25 ± 2.7 µg/mL. Meanwhile, the IC50 of HepG-2 cell inhibition by LSM at a strontium content of 0.2 was 6.73 ± 0.4 µg/mL, and the value increased with increased Sr2+ ion concentration by up to 0.8 to be 31± 3.1 µg/mL. All LSM samples at different conditions were tested as antimicrobial agents towards fungi, Gram positive bacteria, and Gram negative bacteria. For instance, all LSM samples were found to be active towards Gram negative bacteria Escherichia coli, whereas some samples have presumed antimicrobial effect towards Gram negative bacteria Proteus vulgaris. Such results confirmed that LSM samples possessed cytotoxicity against CACO-2 and HepG-2 cells, and they could be considered to play a substantial role in pharmaceutical and therapeutic applications.

Tin-zinc-oxide nanocomposites (SZO) as promising electron transport layers for efficient and stable perovskite solar cells.

Tin-zinc-oxide nanocomposites (SZO) with various Sn : Zn ratios were successfully fabricated and tested as electron transport layers (ETLs) in perovskite solar cells (PVSCs). The fabricated nanocomposites showed good crystallinity, good contact between layers, good electrical conductivity, and favorable light absorption, resulting in an enhancement in the net efficiency of CH3NH3PbI3 (MAPI)-based perovskite solar cells. The device made of SZO-Sn0.05 as an ETL showed a maximum power conversion efficiency (PCE) of 17.81% with a short-circuit current density (J sc) of 23.59 mA cm-2, an open-circuit voltage (V oc) of 1 V, and a fill factor (FF) of 0.754. However, the ETL containing lower Sn ratios showed PCEs of 12.02, 13.80 and 15.86% for pure ZnO, SZO-Sn0.2 and SZO-Sn0.1, respectively. Meanwhile, the reproducibility of 30 fabricated devices proved the outstanding long-term stability of the cells based on SZO nanocomposites, retaining ≈85% of their PCE over 1200 h of operation. In addition, the incident-photon-to-current efficiency (IPCE) exceeded 90% over the entire wavelength range from 400 to 800 nm. The enhancement in the PCE of the fabricated PVSCs can be ascribed to the large surface area of the SZO nanoparticles, high charge extraction efficiency, and suppression of charge recombination provided by SnO x . The current results suggest that our synthesized tin-zinc-oxide nanocomposite is an effective electron transport layer for efficient and stable perovskite solar cells.