The origin of high conductivity in polymer electrodes based on poly(3,4‐ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is investigated and the resilience against water exposure is tested. Post‐treatment with weak and strong acids, namely, hydrochloric acid (HCl), formic acid (HCOOH), nitric acid (HNO3), and sulfuric acid (H2SO4), is performed and compared to the commonly used ethylene glycol treatment. PEDOT:PSS electrodes with electrical conductivities of up to ≈3000 S cm−1 and high transmittance are obtained. The underlying mechanisms for enhanced conductivity are elucidated by means of electrical (4‐point probe), optical (UV‐Vis spectroscopy), compositional (X‐ray photo‐electron spectroscopy), and structural (grazing‐incidence wide‐angle X‐ray scattering, GIWAXS) characterizations. Selective PSS removal and structural rearrangement of PEDOT‐rich domains due to an enhanced lamellar stacking is identified as major influence on the improvement in electrical conductivity. This beneficial high order is evidenced via additional signals in the GIWAXS patterns, which are altered by subsequent H2O treatment. The PSS removal and structural rearrangement is linked to the acids' strength and dielectric constant. High conductivities are reached by efficient PSS removal via HNO3 or H2SO4 treatment with the drawback of high sensitivity against H2O. By contrast, HCl and HCOOH treatment obtaining a medium enhanced conductivity differ in the amount of PSS removal but show higher H2O resistance.

Covalently bonded organic monolayers play important roles in defining the solution processability, ambient stability, and electronic properties of two-dimensional (2D) materials such as Ge nanosheets (GeNSs); they also hold promise of providing avenues for the fabrication of future generation electronic and optical devices. Functionalization of GeNS normally involves surface moieties linked through covalent Ge−C bonds. In the present contribution we extend the scope of surface linkages to include Si−Ge bonding and present the first demonstration of heteronuclear dehydrocoupling of organosilanes to hydride-terminated GeNSs obtained from the deintercalation and exfoliation of CaGe2. We further exploit this new surface reactivity and demonstrated the preparation of directly bonded silicon quantum dot-Ge nanosheet hybrids.

Based on a diblock‐copolymer templated sol–gel synthesis, germanium nanocrystals (GeNCs) are introduced to tailor mesoporous titania (TiO2) films for obtaining more efficient anodes for photovoltaic applications. After thermal annealing in air, the hybrid films with different GeNC content are investigated and compared with films undergoing an argon atmosphere annealing. The surface and inner morphologies of the TiO2/GeOx nanocomposite films are probed via scanning electron microscopy and grazing‐incidence small‐angle X‐ray scattering. The crystal phase, chemical composition, and optical properties of the nanocomposite films are examined with transmission electron microscopy, X‐ray photoelectron spectroscopy, and ultraviolet–visible spectroscopy. Special focus is set on the air‐annealed nanocomposite films since they hold greater promise for photovoltaics. Specifically, the charge–carrier dynamics of these air‐annealed nanocomposite films are studied, and it is found that, compared with pristine TiO2 photoanodes, the GeNC addition enhances the electron transfer, yielding an increase in the short‐circuit photocurrent density of exemplary perovskite solar cells and thus, an enhanced device efficiency as well as a significantly reduced hysteresis.

Schematic representation of dehydrocoupling of H-GeNPs with alkylsilanes, and Electron Energy Loss Spectroscopy (EELS) line scan of alkylsilane passivated GeNPs showing Si on the surface and Ge in the core.

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