Teresa Gatti

Functionalization of transparent conductive oxide electrode for TiO2-free perovskite solar cells

Many of the best performing solar cells based on perovskite-halide light absorbers use TiO2 as an electron selective contact layer. However, TiO2 usually requires high temperature sintering, is related to electrical instabilities in perovskite solar cells, and causes cell performance degradation under full solar spectrum illumination. Here we demonstrate an alternative approach based on the modification of transparent conductive oxide electrodes with self-assembled siloxane-functionalized fullerene molecules, eliminating TiO2 or any other additional electron transporting layer. We demonstrate that these molecules spontaneously form a homogenous monolayer acting as an electron selective layer on top of the fluorine doped tin oxide (FTO) electrode, minimizing material consumption. We find that the fullerene-modified FTO is a robust, chemically inert charge selective contact for perovskite based solar cells, which can reach 15% of stabilised power conversion efficiency in a flat junction device architecture using a scalable, low temperature, and reliable process. In contrast to TiO2, devices employing a molecularly thin functionalized fullerene layer show unaffected performance after 67 h of UV light exposure.

Neuronal commitment of human circulating multipotent cells by carbon nanotube-polymer scaffolds and biomimetic peptides

AIM We aimed to set up a self-standing, biomimetic scaffold system able to induce and support per se neuronal differentiation of autologous multipotent cells. MATERIALS & METHODS We isolated a population of human circulating multipotent cells (hCMCs), and used carbon nanotube/polymer nanocomposite scaffolds to mimic electrical/nanotopographical features of the neural environment, and biomimetic peptides reproducing axon guidance cues from neural proteins. RESULTS hCMCs showed high degree of stemness and multidifferentiative potential; stimuli from the scaffolds and biomimetic peptides could induce and boost hCMC differentiation toward neuronal lineage despite the absence of exogenously added, specific growth factors. CONCLUSION This work suggests the scaffold-peptides system combined with autologous hCMCs as a functional biomimetic, self-standing prototype for neural regenerative medicine applications.

Physico-Chemical, Electrochemical and Structural Insights Into Poly(3,4-ethylenedioxythiophene) Grafted from Molecularly Engineered Multi-Walled Carbon Nanotube Surfaces

Composites of multi-walled carbon nanotubes (MWCNTs) and poly(3,4-ethylenedioxythiophene) (PEDOT) are attracting the attention of material scientists since more than a decade as potential next-generation optoelectronic materials for their peculiar features, arising from the combination of the intrinsic electrical, thermal and morphological properties of the two components. They are indeed a promising platform for the development of low-cost, portable and environmentally friendly electronic devices such as supercapacitors, sensors and actuators. Here a novel synthetic strategy for their preparation is envisaged, exploiting the possibility to covalently functionalize the external surface of MWCNTs with tailored molecular units, starting from which the growth of the conjugated polymer can be induced oxidatively. The approach demonstrates its value in being able to effectively promote the formation of PEDOT chains in direct contact with the surface of MWCNTs, differently from what results when the monomer is polymerized in the presence of the pristine carbon nanomaterial. In addition, significant differences are found in the physico-chemical properties and electrochemical behavior when MWCNT-PEDOT covalent composites are studied in comparison to a non-covalent analogue, here illustrated in detail. These evidences constitute a starting point for the future development of novel more finely tuned functional materials based on MWCNT-PEDOT composites, featuring the required optoelectronic properties to precisely target the desired application.

Perovskite solar cells stabilized by carbon nanostructure-P3HT blends

We present the use of covalently functionalized carbon nanostructures (CNSs) such as single-wall carbon nanotubes (SWCNTs) and graphene nanoplatelets (GNPs), as conductive nanofillers in a P3HT matrix. We propose a simple approach for the preparation of the active blends used as hole transport layer (HTL) in mesoporous perovskite solar cells (PSCs). We demonstrate that for both SWCNT and GNP nanofillers, power conversion efficiencies (~10%) and shelf life stabilities (over 3240 hours) are improved with respect to PSCs using bare P3HT as the HTL.