Printable Counter Electrode with Metal Nitride as the Conductive Medium for Perovskite Solar Cells.

Perovskite solar cells (PSCs) with a booming high power conversion efficiency (PCE) are on their road toward industrialization. A proper design of the counter electrode (CE) with low cost, high conductivity, chemical stability, and good interface contact with the other functional layer atop the perovskite layer is vital for the overall performance of PSCs. Herein, the application of titanium nitride (TiN) is reported as a conductive medium for the printable CE in hole-conductor-free mesoscopic PSCs. TiN improves the conductivity of the CE and reduces the resistivity from 20 to 10 mΩ∙cm. TiN also improves the wettability of the CE with perovskite and enhances the back interface contact, which promotes charge collection. On the other hand, TiN is chemically stable during processing and undergoes no distinguishable chemical reaction with halide perovskite. Devices with TiN as the conductive media in the CE deliver a champion PCE of 19.01%. This work supplies a considerable choice for the CE design of PSCs toward industrial applications.

Study on the Reactivity Activation of Coal Gangue for Efficient Utilization.

In this study, the research aim is to enhance the activity index of activated coal gangue and study its activation mechanism. The activation process of coal gangue was optimized through orthogonal tests, and the Back-Propagation (BP) neural network model was improved using a genetic algorithm. With the effects of grinding duration, calcination temperature, and calcination duration, the morphological changes and phase transformation processes of coal gangue were studied at the micro and meso levels to clarify the activation mechanism. The results indicated that the effect of calcination temperature on the strength activity index of coal gangue was most significant, followed by grinding duration and calcination duration. The potential activity of coal gangue can be effectively stimulated through mechanical and thermal activation, and the content of potential active minerals in coal gangue powders was also increased. The activation process of coal gangue for the optimal scheme was obtained as grinding at 76 min first and thermal treatment at 54 min at 749 °C. As the thermal activation under 950 °C, some unstable external hydroxyls, and internal hydroxyls in kaolinite from coal gangue were removed, the AlⅥ-O octahedron was destroyed, and kaolinite was transformed into spatially disordered metakaolinite with very high activity.

Interfacial Energy Band Alignment Enables the Reduction of Potential Loss for Hole-Conductor-Free Printable Mesoscopic Perovskite Solar Cells.

Perovskite solar cells (PSCs) have achieved high efficiencies with diversified device architectures. In particular, printable mesoscopic PSC has attracted intensive research attention due to its simple fabrication process and superior stability. However, in the absence of hole conductors, the unfavorable energy band alignment between the perovskite and the carbon electrode usually leads to the reduction of device performance, especially the open-circuit voltage (VOC). Here, a p-type molecule, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), is utilized to post-treat the perovskite/carbon interface, which benefits the charge transfer and suppresses the charge recombination within the device. As a result, the post-treated device delivers a power conversion efficiency of 18.05% with an enhanced VOC of 1044 mV. This work provides a facile method for tuning the interfacial energy band alignment and improving performance of printable mesoscopic PSCs.

Identification of a novel Soybean mosaic virus isolate in China that contains a unique 5' terminus sharing high sequence homology with Bean common mosaic virus.

Two soybean viral isolates 4469-4 and Sc6 from plants in China were characterized by serological assays, pathogenicity tests, full-genome sequencing and sequence analyses. Both isolates are determined to be Soybean mosaic virus (SMV) isolates but 4469-4 is different from other known SMVs by inducing symptoms on common bean. 4469-4 has an RNA genome of 9994 nucleic acids (nt) encoding 3202 amino acids (aa), which is approximately 400 nt longer than that of Sc6 and other SMV strains. Comparison with SMV and SMV-related potyviruses suggests that 4469-4 shares high nt and aa sequence identify (>92%) with other SMV strains. However, significant diversity between 4469-4 and other SMV strains was observed in the 5' genomic region. In contrast, this region is highly similar to the corresponding region of Bean common mosaic virus (BCMV). Recombination analyses conclude that there is a recombination site near the nt 900 of 4469-4. Taken together these data suggest that 4469-4 may result from recombination between SMV and BCMV or a BCMV-like virus in the N-terminus of the genome.