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Colloidal lead‐free perovskite nanocrystals have recently received extensive attention because of their facile synthesis, the outstanding size‐tunable optoelectronic properties, and less or no toxicity in their commercial applications. Tin (Sn) has so far led to the most efficient lead‐free solar cells, yet showing highly unstable characteristics in ambient conditions. Here, we propose the synthesis of all‐inorganic mixture Sn‐Ge perovskite nanocrystals, demonstrating the role of Ge2+ in stabilizing Sn2+ cation while enhancing the optical and photophysical properties. The partial replacement of Sn atoms by Ge atoms in the nanostructures effectively fills the high density of Sn vacancies, reducing the surface traps and leading to a longer excitonic lifetime and increased photoluminescence quantum yield. The resultant Sn‐Ge nanocrystals‐based devices show the highest efficiency of 4.9 %, enhanced by nearly 60 % compared to that of pure Sn nanocrystals‐based devices. [ABSTRACT FROM AUTHOR]

Terpyridine-substituted perylenes containing cyclic anhydrides in the peri position were synthesized. The anhydride group served as an anchor for assembly of the terpyridyl-crowned chromophores as monomolecular layers on metal oxide surfaces. Further coordination with Zn2+ ions allowed for layer-by-layer formation of supramolecular assemblies of perylene imides on the solid substrates. With properly selected anchor and linker molecules it was possible to build high quality structures of greater than ten successive layers by a simple and straightforward procedure. The prepared films were stable and had a broad spectral coverage and high absorbance. To demonstrate their potential use, the synthesized dyes were employed in solid-state dye-sensitized solar cells, and electron injection from the perylene antennas to titanium dioxide was observed. [ABSTRACT FROM AUTHOR]

The most commonly used hole transporting layer (HTL) in conventional polymer solar cells is poly(3,4-ethylenedioxythiophene)poly(styrenesulfonate) PEDOT:PSS. The acidic nature of this HTL is responsible for etching of the indium tin oxide (ITO) layer which is the anode in polymer solar cells and leads to degradation of efficiency in polymer solar cells in the long run. In this article we explored the effect of plasma treated Ag as an intermediate layer between ITO and PEDOT:PSS for over one month period. It was found that the devices with plasma treated Ag as an intermediate layer with thickness of 5 nm resulted in only 30% degradation over one month and did not decrease the initial power conversion efficiency (PCE) compared to the cell without the anode modification, whereas the devices without the intermediate layer, degraded up to 66% of the initial PCE. The mechanism was analyzed using XPS measurements and found out that indium from ITO etches out and diffuses to the subsequent polymer layer. Further, the experiment revealed that the presence of plasma treated Ag layer restricted the rapid indium diffusion, which accounted to enhanced device stability. [ABSTRACT FROM AUTHOR]