High-performance bifacial perovskite solar cells enabled by single-walled carbon nanotubes.

Bifacial perovskite solar cells have shown great promise for increasing power output by capturing light from both sides. However, the suboptimal optical transmittance of back metal electrodes together with the complex fabrication process associated with front transparent conducting oxides have hindered the development of efficient bifacial PSCs. Here, we present a novel approach for bifacial perovskite devices using single-walled carbon nanotubes as both front and back electrodes. single-walled carbon nanotubes offer high transparency, conductivity, and stability, enabling bifacial PSCs with a bifaciality factor of over 98% and a power generation density of over 36%. We also fabricate flexible, all-carbon-electrode-based devices with a high power-per-weight value of 73.75 W g-1 and excellent mechanical durability. Furthermore, we show that our bifacial devices have a much lower material cost than conventional monofacial PSCs. Our work demonstrates the potential of SWCNT electrodes for efficient, stable, and low-cost bifacial perovskite photovoltaics.

Interfacial Chemical Bridging Constructed by Multifunctional Lewis Acid for Carbon Nanotube/Silicon Heterojunction Solar Cells with an Efficiency Approaching 17.7.

Single-wall carbon nanotube/silicon (SWCNT/Si) heterojunction shows appealing potential for use in photovoltaic devices. However, the relatively low conductivity of SWCNT network and interfacial recombination of carriers have limited their photovoltaic performance. Herein, a multifunctional Lewis acid (p-toluenesulfonic acid, TsOH) is used to significantly reduce the energy loss in SWCNT/Si solar cells. Owing to the charge transfer doping effect of TsOH, the conductivity and work function of SWCNT films are optimized and tuned. More importantly, a chemical bridge is constructed at the interface of SWCNT/Si heterojunction. Experimental studies indicate that the phenyl group of TsOH can interact with SWCNTs through π-π interaction, meanwhile, the oxygen in the sulfonic functional group of the TsOH molecule can graft on the dangling bonds of the Si surface. The chemical bridge structure effectively suppresses the recombination of photogenerated carriers. The TsOH coating also works as an antireflection layer, leading to a 19% increment of the photocurrent. As a result, a champion power conversion efficiency of 17.7% is achieved for the TsOH-SWCNT/Si device, and it also exhibits an excellent stability, retaining more than 96% of the initial efficiency in the ambient air after 1 month.

Fermi-Level Depinning in Metal/Ge Junctions by Inserting a Carbon Nanotube Layer.

Germanium (Ge)-based devices are recognized as one of the most promising next-generation technologies for extending Moore's law. However, one of the critical issues is Fermi-level pinning (FLP) at the metal/n-Ge interface, and the resulting large contact resistance seriously degrades their performance. The insertion of a thin layer is one main technique for FLP modulation; however, the contact resistance is still limited by the remaining barrier height and the resistance induced by the insertion layer. In addition, the proposed depinning mechanisms are also controversial. Here, the authors report a wafer-scale carbon nanotube (CNT) insertion method to alleviate FLP. The inserted conductive film reduces the effective Schottky barrier height without inducing a large resistance, leading to ohmic contact and the smallest contact resistance between a metal and a lightly doped n-Ge. These devices also indicate that the metal-induced gap states mechanism is responsible for the pinning. Based on the proposed technology, a wafer-scale planar diode array is fabricated at room temperature without using the traditional ion-implantation and annealing technology, achieving an on-to-off current ratio of 4.59 × 104 . This work provides a new way of FLP modulation that helps to improve device performance with new materials.

[Oxidation stress and toxicity of TBBPA pollution on polychaete tubifex (Monopylephorus limosus)].

Using the indoor simulating method of dynamic and static exposure respectively, the toxic effects of TBBPA on the antioxidant enzyme defense systems and Glutathione-S-transferase (GST) activity of tubifex Monopylephorus limosus were examined. The activity of superoxide dismutase (SOD) and catalase (CAT) with time was also examined. The results showed that after an 8 d exposure, the SOD activity was enhanced at first and then inhibited gradually, at last enhanced again. The highest activity of SOD (p < 0.01) was examined under 0.05 mg/L concentration of TBBPA. And the activity of SOD was much higher than that of control (1.5-7.8 times more than that of the control). The activity of CAT showed a tendency of induction firstly and then inhibition, then induction again and at last inhibition, reached the highest value under 0.5 mg/L of TBBPA. Furthermore, the CAT activity was higher than that of the control (1.1-1.9 times more than that of the control) except that under 0.005 mg/L and 0.25 mg/L of TBBPA. Moreover, the highest activity of GST (p < 0.01) was observed under 0.25 mg/L of TBBPA. The activity of GST was enhanced gradually at first and then inhibited. As the same as SOD, the activity of GST was induced significantly (p < 0.05). The changes in the SOD activity showed an "M" trend,while that in the CAT activity showed an "N" trend. And the activity of SOD is steadier than that of CAT. Thus, changes in the activity of SOD and GST, especially SOD, can better reflect the toxic effects of pollutants on tubifex.

[Researching progresses in environmental pollution behavior, toxic effects and mechanisms of PFOS/PFOA].

It has been validated that perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) can be considered as emerging persistent organic pollutants. In recent years, there are increasing distribution of PFOS/PFOA in environmental systems, and accumulation and toxic effects of PFOS/PFOA in living organisms. Thus, environmental pollution and biological exposure of PFOS/PFOA were firstly analyzed on the basis of their pollution levels, exposure to wild animals, exposure to human bodies, and changing trends in pollution and exposure. Secondly, movement and transformation behaviors of PFOS/PFOA in environment were expounded on the basis of their transport and transformation processes in air environment, wastewater and sewage sludge, and their accumulation, metabology and degradation processes in living organisms. Some recent important advances in ecological effects of PFOS/PFOA and their possible mechanisms were summarized. Finally, the future emphases of research on pollution ecology of PFOS/PFOA were tentatively suggested.