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Gallium nitride nanowire and nanorod substrates are prospective platforms allowing to control the local strain distribution in graphene films on top of them, resulting in an induction of pseudomagnetic fields. AFM measurements performed in a HybriD mode complemented by SEM allow for a detailed visualization of the strain distribution on graphene surface. Graphene in direct contact with supporting regions is tensile strained, while graphene located in-between is characterized by lower strain. Characteristic tensile strained wrinkles also appear in the areas between the supporting regions. A positive correlation between strain gradient and distances between borders of supporting regions is observed. These results are confirmed by analysis of the Raman D’ band intensity, which is affected by an enhancement of intravalley scattering. Furthermore, scanning tunneling spectroscopy shows a local modification of the density of states near the graphene wrinkle and weak localization measurements indicate the enhancement of pseudomagnetic field-induced scattering. Therefore, we show that nanowire and nanorod substrates provide strain engineering and induction of pseudomagnetic fields in graphene. The control of graphene morphology by modification of distances between supporting regions is promising for both further fundamental research and the exploration of innovative ways to fabricate pseudomagnetic field-based devices like sensors or filters.

In this paper, new cost-effective platinum-free and flexible counter electrodes (CEs) for dye-sensitized solar cells (DSSCs) were reported. The ITO/PET CEs were produced using graphene films synthesized by CVD method and graphene flakes with addition PEDOT: PSS or PEDOT: PSS/PVP. The influence of mechanical stress arising from the bending of a flexible substrate on morphology, resistance of CEs as well as electrical properties of DSSCs was analyzed. The testing of these electrodes in DSSCs have demonstrated a power conversion efficiency of up to 3.95% to compare with the power conversion efficiency of 4.39% for DSSC with a standard Pt-based CE. After 100 bending cycles the electrodes demonstrated power conversion efficiency in range the 2.37–3.23% to compare with the power conversion efficiency of 2.08% for DSSC with a standard Pt-based CE. HRTEM investigation confirms the crystallographic structure of graphene. The obtained results demonstrate the possibility of replacing expensive platinum in DSCC by using graphene-based counter electrode.