Effect of Pristine Graphene on Methylammonium Lead Iodide Films and Implications on Solar Cell Performance

Abstract

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.

Enhancing Stability and Resistive Memory Performance: The Role of Graphene in Hybrid Perovskite Composites

“…Previous studies have reported that a lower concentration of graphene may lower the activation energy. 42 However, in our composite system, the concentration of graphene is too low that it may have minimal effect on the activation energy. Figure 7e shows a schematic arrangement of filament formation by the bromide vacancies (V Br ).…”

“…The increase in resistivity with temperature is just opposite nature of semiconductor. 42 This implies the role of graphene in the composite system as a conductive medium, due to which a small increase in resistivity is observed in the D2 device. Furthermore, the Schottky barrier is also reduced during the voltage bias to boost the charge injection through the ITO/g-FAPbBr 3 interface.…”

“…Therefore, under external electric field the migration rate will be high . The value of E A can be obtained from the expression for thermally activated conduction ρ = ρ 0 e − E A / K T where ρ is the resistivity, ρ 0 is the pre-exponential factor, and K is the Boltzmann constant at absolute temperature T . The temperature-dependent I – V measurement has also been carried out for the D1 device, as shown in Figure S8a (Supporting Information).…”

Applications of Carbon‐Based Materials for Improving the Performance and Stability of Perovskite Solar Cells

“…Recently, a small concentration of graphene platelet (G‐platelet) was also incorporated in the active layer of a solar cell to study its effect on structural, optical properties, and device performance. [ 158 ] The impermeable nature to gases and hydrophobic nature of graphene sealed the surface of grains resulting in low ionic diffusion. In addition, the presence of graphene enlarged the crystalline domain along with its high preferential orientation, and increased the porosity of films and photovoltaic parameters.…”

Sensitivity of SnO2 nanoparticles/reduced graphene oxide hybrid to NO2 gas: A DFT study

“…Graphene is a material with high potential applications [1][2][3]. These applications include solar cells [1], LEDs [2], and many other applications [3]. The same is true for graphene oxide [4].…”