A vacancy‐ordered double perovskite, Cs2SnI6, has emerged as a promising lead‐free perovskite in the optoelectronic field. However, the charge transfer kinetics mediated by its surface state remains unclear. Here, the charge transfer mechanism of Cs2SnI6 is reported and the role of its surface state in the presence of a redox mediator is clarified. Specifically, charge transfer through the surface state of Cs2SnI6 and its subsequent surface state charging are demonstrated by cyclic voltammetry and Mott–Schottky measurements, respectively. Because it is expected that the surface state of Cs2SnI6 is capable of regenerating oxidized organic dyes, a Cs2SnI6‐based regenerator is developed for a dye‐sensitized solar cell composed of fluorine‐doped tin oxide (FTO)/dyed mesoporous TiO2/regenerator/poly(3,4‐ethylenedioxythiophene)/FTO. As expected, the performance of the Cs2SnI6‐based regenerator is strongly dependent on the highest occupied molecular orbital of the dyes. Consequently, Cs2SnI6 shows efficient charge transfer with a thermodynamically favorable charge acceptor level, achieving a 79% enhancement in the photocurrent density (14.1 mA cm−2) compared with that of a conventional liquid electrolyte (7.9 mA cm−2). The results suggest that the surface state of Cs2SnI6 is the main charge transfer pathway in the presence of a redox mediator and should be considered in future designs of Cs2SnI6‐based devices.

Benzo[c][1,2,5]thiadiazole (BT) has been used in dye-sensitized solar cells (DSCs) for its light-harvesting abilities. However, as a strongly electron deficient unit, BT causes rapid back electron transfer (BET), which in turn lowers the photoconversion efficiency (PCE) of devices. Herein, we report a powerful strategy for retarding BET by controlling both the photoelectrode thickness and π-spacer dihedral angle.To achieve this, we introduced planar (BT-T) or twisted πspacers (BT-P, BT-MP, and BT-HT) between BT units and anchoring groups and used different photoelectrode thicknesses between 1.8 and 10 μm. Computational and experimental results show that twisted π-spacers were more efficient at retarding BET than the planar π-spacer. However, BET was found to be less important than expected, and light harvesting efficiency (LHE) played a critical role as the thickness of the photoelectrode decreased because charge collection efficiency was enhanced. The planar dye BT-T obtained the highest LHE, this value remained unusually high even in 1.8 μm photoelectrodes. As a result, BT-T gave a PCE of 6.5% (J sc = 13.56 mA/ cm 2 , V oc = 0.67 V, and FF = 0.72) in thin 1.8 μm photoelectrodes with 3.5 μm scattering layers, which represented a roughly 40% enhancement compared to the PCE in 10 μm photoelectrodes (4.76%). Overall, these results provide a novel approach to achieving ultrathin and highly efficient flexible DSCs.

BackgroundThe association between obesity and albuminuria in the general population remains unclear. We aimed to identify the association between obesity and albuminuria as well as sex differences regarding the associations using several obesity indices, including waist circumference (WC), body mass index (BMI), and waist-to-height ratio (WHR).MethodsThis study included 3841 subjects (1730 males and 2111 females; age 20–80 years) who participated in the Fifth Korea National Health and Nutrition Examination Survey conducted in 2011. Subjects with hypertension, diabetes, renal failure, or a malignant tumor and those who were pregnant or menstruating were excluded. Albuminuria was defined as a urinary albumin-to-creatinine ratio ≥30 mg/g. Anthropometric parameters were categorized into sex-specific quartiles. Logistic regression models were used to assess the associations between each anthropometric parameter and albuminuria.ResultsAll of the obesity indices of the fourth quartile group of females showed a twofold higher risk for albuminuria than the second quartile group, and it was persistently significant after adjusting for age, smoking, and physical activity. After further adjustment for high blood pressure and impaired fasting glucose and triglyceride levels, WC and BMI of the fourth quartile group of females still showed a significantly higher risk for albuminuria than the second quartile group (odds ratios 1.96 and 2.24; 95 % confidence intervals 1.03–3.74 and 1.15–4.37). None of the associations between albuminuria and the obesity indices were significant in males.ConclusionHigher WC and BMI were significantly associated with the risk of albuminuria among females, but not males.Electronic supplementary materialThe online version of this article (doi:10.1007/s10157-016-1238-z) contains supplementary material, which is available to authorized users.

The photo-, thermal, and water stability of dyes is indispensable for the commercialization of dye-sensitized solar cells, necessitating the development of systematic molecular design strategies to enhance the stability of the dyes. Therefore, we prepared dithieno­[3,2-b:2′,3′-d]­thiophene (DTT)-based dyes, by varying the functional group on the donor moiety (TP-1, H-; TP-2, methoxy-; TP-3, carbazolyl-; and TP-4, 2-ethylhexyloxy-). Among these dyes, TP-4 exhibits the highest power conversion efficiency of 8.86% (J sc = 15.9 mA cm–2, V oc = 0.76 V, FF = 0.73) with iodine electrolyte on a thin TiO2 active layer (3.5 μm), as well as strong resistance to photo-, thermal, and water stresses. UV–vis spectroscopy, intensity-modulated photocurrent spectroscopy, and intensity-modulated photovoltaic spectroscopy were used to analyze the dyes. On the basis of these analyses, we suggest a molecular design strategy for simultaneously enhancing the stability of photo-, thermal, and water stresses.

No abstract