The micellization process of the aqueous mixed system Triton X-100 (TX100) -Dodecyltrimethylammonium Bromide (DTAB) was studied with a battery of procedures: surface tension, static and dynamic light scattering and ion-selective electrodes. Results were also analysed with two thermodynamic procedures. The system shows some changes in its behaviour with changing the mole fraction of DTAB, DTAB, in the whole surfactant mixture. For DTAB  0.40 micelles are predominantly TX100 with scarce solubilized DTA + ions, and TX100 acts as a nearly ideal solvent. In the range 0.50  DTAB  0.75 it seems that none of the components acts as a solvent, and above DTAB  0.75 there are abrupt changes in the size and electrophoretic mobility of micelles.These phenomena have been interpreted in the light of the thermodynamic results and some TX100-ionic surfactant mixtures of literature.

The relatively low stability of solar cells based on hybrid halide perovskites is the main issue to be solved for the implementation in real life of these extraordinary materials. Degradation is accelerated by temperature, moisture, oxygen, and light and mediated by halide easy hopping. The approach here is to incorporate pristine graphene, which is hydrophobic and impermeable to gases and likely limits ionic diffusion while maintaining adequate electronic conductivity. Low concentrations of few-layer graphene platelets (up to 24 × 10 –3 wt %) were incorporated to MAPbI 3 films for a detailed structural, optical, and transport study whose results are then used to fabricate solar cells with graphene-doped active layers. The lowest graphene content delays the degradation of films with time and light irradiation and leads to enhanced photovoltaic performance and stability of the solar cells, with relative improvement over devices without graphene of 15% in the power conversion efficiency, PCE. A higher graphene content further stabilizes the perovskite films but is detrimental for in-operation devices. A trade-off between the possible sealing effect of the perovskite grains by graphene, that limits ionic diffusion, and the reduction of the crystalline domain size that reduces electronic transport, and, especially, the detected increase of film porosity, that facilitates the access to atmospheric gases, is proposed to be at the origin of the observed trends. This work demonstrated how the synergy between these materials can help to develop cost-effective routes to overcome the stability barrier of metal halide perovskites, introducing active layer design strategies that allow commercialization to take off.

MA0.5FA0.5PbI3, increasing the average photoconversion efficiency (PCE) respect the reference cell by 18, 32 and 4 % respectively, observed for regular, n-i-p, and inverted, p-i-n, solar cell configurations. This analysis highlights the generality of this approach for halide perovskite materials in order to reduce non-radiative recombination as observed by impedance spectroscopy.