On the Conformation of Dimeric Acceptors and Their Polymer Solar Cells with Efficiency over 18 %

The determination of molecular conformations of oligomeric acceptors (OAs) and their impact on molecular packing are crucial for understanding the photovoltaic performance of their resulting polymer solar cells (PSCs) but have not been well studied yet. Herein, we synthesized two dimeric acceptor materials, DIBP3F-Se and DIBP3F-S, which bridged two segments of Y6-derivatives by selenophene and thiophene, respectively. Theoretical simulation and experimental 1D and 2D NMR spectroscopic studies prove that both dimers exhibit O-shaped conformations other than S- or U-shaped counter-ones. Notably, this O-shaped conformation is likely governed by a distinctive “conformational lock” mechanism, arising from the intensified intramolecular π–π interactions among their two terminal groups within the dimers. PSCs based on DIBP3F-Se deliver a maximum efficiency of 18.09 %, outperforming DIBP3F-S-based cells (16.11 %) and ranking among the highest efficiencies for OA-based PSCs. This work demonstrates a facile method to obtain OA conformations and highlights the potential of dimeric acceptors for high-performance PSCs

Analysis of the Associations between Vitamin D and Albuminuria or β-Cell Function in Chinese Type 2 Diabetes

Objective. To investigate the associations of 25-(OH)D and β-cell function or insulin resistance or albuminuria in Chinese type 2 diabetic patients. Methods. In total, 1408 type 2 diabetic patients without vitamin D supplement were included in this retrospective study. Results. Comparison between patients with and without 25-(OH)D deficiency indicated that, compared with patients with 25-(OH)D ≥ 50 nmol/L, patients with 25-(OH)D < 50 nmol/L showed a higher level of urine albumin-creatinine ratio (ACR) (90.15±10.30 mg/g versus 52.79±14.97 mg/g). Multiple regression analysis indicated that 25-(OH)D was independently and negatively correlated with urine ACR (OR=0.985, 95%CI 0.972–0.999, P=0.03), adjusted by age, diabetic duration, HBP duration, SBP, HbA1c, creatinine, LDL-C, triglyceride, total cholesterol, and HDL-C. Compared with patients with normal level of urine ACR, patients with higher level of urine ACR showed a significant lower level of 25-(OH)D (34.49±13.52 nmol/L versus 37.46±13.6 nmol/L, P=0.00). Analysis of the associations of 25-(OH)D and β-cell function or insulin resistance showed that 25-(OH)D may not correlate with β-cell function or insulin resistance. Conclusion. 25-(OH)D was independently associated with albuminuria in Chinese type 2 diabetic patients but was not associated with β-cell function or insulin resistance

Excellent Passivation of Silicon Surfaces by Thin Films of Electron-Beam-Processed Titanium Dioxide

Dielectric of a titanium dioxide thin film is currently re-emerging as a passivating material for high-efficiency crystalline silicon (c-Si) solar cells, owing to its good passivation quality and appropriate band offset when in contact with c-Si. Here, we demonstrate effective passivation on c-Si substrates by electron-beam-processed titanium oxide layers, which are obtained by low-temperature thermal oxidation of predeposited pure titanium thin films. A derived titanium oxide layer by 3.5-nm titanium at 250 degrees C yields a surface recombination velocity down to 16 cm/s. Structural characterizations reveal that the resultant oxide layers are amorphous titanium dioxide. The passivation property is attributed to Si-O-Ti bonding at the Si-titanium dioxide interface as well as to the presence of an interfacial silicon dioxide layer. The easy processing and high-level passivation capability make these titanium dioxide thin films highly desirable to serve as a good passivating choice toward high-efficiency c-Si solar cells

Optoelectronic Evaluation and Loss Analysis of PEDOT:PSS/Si Hybrid Heterojunction Solar Cells

Abstract The organic/silicon (Si) hybrid heterojunction solar cells (HHSCs) have attracted considerable attention due to their potential advantages in high efficiency and low cost. However, as a newly arisen photovoltaic device, its current efficiency is still much worse than commercially available Si solar cells. Therefore, a comprehensive and systematical optoelectronic evaluation and loss analysis on this HHSC is therefore highly necessary to fully explore its efficiency potential. Here, a thoroughly optoelectronic simulation is provided on a typical planar polymer poly (3,4-ethylenedioxy thiophene):polystyrenesulfonate (PEDOT:PSS)/Si HHSC. The calculated spectra of reflection and external quantum efficiency (EQE) match well with the experimental results in a full-wavelength range. The losses in current density, which are contributed by both optical losses (i.e., reflection, electrode shield, and parasitic absorption) and electrical recombination (i.e., the bulk and surface recombination), are predicted via carefully addressing the electromagnetic and carrier-transport processes. In addition, the effects of Si doping concentrations and rear surface recombination velocities on the device performance are fully investigated. The results drawn in this study are beneficial to the guidance of designing high-performance PEDOT:PSS/Si HHSCs. PACS: 85.60.-q, Optoelectronic device, 84.60.Jt, Photovoltaic conversion

Monolithic Perovskite-Perovskite-Organic Triple-Junction Solar Cells with a Voltage Output Exceeding 3 V

Monolithic integration of perovskite-perovskite-organic subcells yields a triple-junction solar cell with a record open-circuit voltage of 3.03 V and a power conversion efficiency of 19.4%. The proposed triple-junction architecture represents a milestone toward scalable photovoltaics, targeting efficiencies beyond the limit of single-junction devices.</p