Yanqiang Li

Incredible PCE enhancement induced by damaged perovskite layers: deeply understanding the working principle of additives in bulk heterojunction perovskite solar cells

The power conversion efficiency (PCE) of perovskite solar cells (PSCs) can be improved by introducing appropriate additives into perovskite precursor solutions. However, the exact role and mechanism of additives are still unclear. In this study, self-designed cognition experiments were conducted to improve the hole extraction efficiency, as well as to deeply understand the working principle of additives. A common hole transport material, 2,2′,7,7′-tetrakis[N,N-di(4-methoxyphenyl) amino]-9,9′-spirobifluorene (spiro-OMeTAD), was used as an additive for bulk heterojunction PSCs (BHJ-PSCs). The results showed that the PCE of mesoporous BHJ-PSCs (M-BHJ-PSCs) was enhanced by more than 15% when an extremely low concentration of spiro-OMeTAD additive was added. However, the crystallization of the perovskite was hampered and the recombination risk increased when grain boundaries increased in the perovskite layer. Planar BHJ-PSCs were fabricated to further investigate the role of additives. In comparison with those in planar BHJ-PSCs, the hole extraction efficiency and diffusion length significantly improved in M-BHJ-PSCs due to the transport paths and relay effects caused by the spiro-OMeTAD additive. Subsequently, exact functions and a new working principle of additives in BHJ-PSCs were proposed. This study may extend the possibilities of designing highly efficient PSCs through the promotion of additive research and application.

Light engineering for bifacial transparent perovskite solar cells with high performance

Abstract. Bifacial transparent perovskite solar cells (BTPSCs) were designed to harvest more solar energy and ensure higher efficiency than conventional PSCs. A series of BTPSCs was successfully prepared using transparent ultrathin Au electrodes with different thicknesses. The transmittance and resistance of Au electrodes played a major role in achieving photo-to-electricity conversion efficiency (PCE). Engineering the light-harvesting ability of the fabricated BTPSCs led to the highest PCE of 14.74%. Reflecting-light intensity and illumination angle were further observed to be the key factors affecting PCE. These BTPSCs could be applied on building integration of photovoltaics (PVs), such as semitransparent PV windows or venetian blinds. Another alternative application is to use these BTPSCs as the wings of unmanned aerial vehicles.

Theoretical and experimental studies of the influence of microstructure on anti-tarnish ability of cyanide-free silver deposit

The influence of microstructure on anti-tarnish ability of silver deposit was studied by computational chemistry and experiments. The influence of microstructure on the anti-tarnish ability of silver deposit was firstly predicted by quantum chemical calculations. Theoretical studies revealed that high-index crystal surfaces of silver deposits were more sensitive to corrosive mediums and were seriously damaged when they were discolored. Based on the prediction of quantum chemical calculations, silver electrodeposition process with crystal surfaces controlled by additives was possible approach to improve the anti-tarnish ability of silver deposit in this work. The anti-tarnish ability of silver deposit influenced by crystal surfaces control was studied by surface discoloration investigation and Tafel plots measurements, as well as X-ray photoelectron spectroscopy (XPS) measurements. The results of these measurements confirmed the conclusions of theoretical studies; silver electrodeposition process with microstructure control can be used to improve the anti-tarnish ability of silver deposit.

A facile approach for the fabrication of loading-controlled Ag/C foam catalyst

A loading-controlled Ag/C foam catalyst prepared by facile electrochemical growth in an environmentally friendly electrolyte with 5,5-dimethylhydantoin (DMH) and niacin (NA) as complexing agents is reported. By controlling the cathodic current density and the growth time, the loading amount of silver on carbon support can be easily controlled. Ag/C foam catalyst with small size, ideal distribution, and controllable loading amount of Ag particles can be obtained on foam carbon support.