evidence of bipolar resistive switching memory in perovskite solar cell

In hybrid inorganic-organic perovskite solar cells a very stable bipolar resistive switching behavior in the dark current-voltage characteristics at low-voltages has been observed. The possible use of the solar cell as an electrical memory with a moderate on-off contrast but very good stability over a prolonged time has been suggested. The reversible behavior and the long dynamics during the write/erase processes indicate that the physical mechanism behind the switching is related to polarization effects. A detailed analysis of the charge carrier trapping/detrapping, transport, and recombination mechanisms has been performed by taking the ion migration and the consequent charge carrier accumulation within the device into account. The charge transport during the write operation can be described by space-charge-limited conduction process. The formation and subsequent interruption of conducting pathways due to ion migration have been identified as the main cause of the resistive switching within the perovskite material. The strong interaction between the ion movement and the electron transport enables the operation of the perovskite solar cell also as a non-volatile memory

Band Bending Effect of LiI/NaI treated TiO2 Photoanode on Performance of Dye-sensitized Solar Cells

A new method has been developed upon surface treatment of TiO2 photoanode with LiI/NaI to enhance the photocurrent and, subsequently, the performance efficiency of the fabricated dye-sensitized solar cells (DSSCs). Three different concentrations (0.1, 0.25, 0.5 mmol%) of LiI and NaI solutions were used to investigate the effect of this surface treatment in terms of DSSCs device performance. The positive shift in the energy level of TiO2 has been experienced by surface treated devices which is predominantly supported by the decrease in VOC. Further, the introduction of LiI/NaI onto the TiO2 surface resulted reduction in crystallite size means increase in surface area which helps more dye adsorption leading to higher JSC values of the devices. Besides, modification of the conduction band energy level, it also allows the fast electron injection process by shifting the density of states. Thus, this approach offers a simple but efficient route to enhance the photocurrent and efficiency of the DSSCs

Identification of Cytoprotective Small-Molecule Inducers of Heme-Oxygenase-1

Acute kidney injury (AKI) is a major public health concern with significant morbidity and mortality and no current treatments beyond supportive care and dialysis. Preclinical studies have suggested that heme-oxygenase-1 (HO-1), an enzyme that catalyzes the breakdown of heme, has promise as a potential therapeutic target for AKI. Clinical trials involving HO-1 products (biliverdin, carbon monoxide, and iron), however, have not progressed beyond the Phase ½ level. We identified small-molecule inducers of HO-1 that enable us to exploit the full therapeutic potential of HO-1, the combination of its products, and yet-undefined effects of the enzyme system. Through cell-based, high-throughput screens for induction of HO-1 driven by the human HO-1 promoter/enhancer, we identified two novel small molecules and broxaldine (an FDA-approved drug) for further consideration as candidate compounds exhibiting an Emax ≥70% of 5 µM hemin and EC50 HMOX1. In vitro, the cytoprotective function of the candidates was assessed against cisplatin-induced cytotoxicity and apoptosis. In vivo, delivery of a candidate compound induced HO-1 expression in the kidneys of mice. This study serves as the basis for further development of small-molecule HO-1 inducers as preventative or therapeutic interventions for a variety of pathologies, including AKI