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Perovskite solar cells (PSC) have been identified as a game-changer in the world of photovoltaics. This is owing to their rapid development in performance efficiency, increasing from 3.5% to 25.8% in a decade. Further advantages of PSCs include low fabrication costs and high tunability compared to conventional silicon-based solar cells. This paper reviews existing literature to discuss the structural and fundamental features of PSCs that have resulted in significant performance gains. Key electronic and optical properties include high electron mobility (800 cm2/Vs), long diffusion wavelength (>1 μm), and high absorption coefficient (105 cm−1). Synthesis methods of PSCs are considered, with solution-based manufacturing being the most cost-effective and common industrial method. Furthermore, this review identifies the issues impeding PSCs from large-scale commercialisation and the actions needed to resolve them. The main issue is stability as PSCs are particularly vulnerable to moisture, caused by the inherently weak bonds in the perovskite structure. Scalability of manufacturing is also a big issue as the spin-coating technique used for most laboratory-scale tests is not appropriate for large-scale production. This highlights the need for a transition to manufacturing techniques that are compatible with roll-to-roll processing to achieve high throughput. Finally, this review discusses future innovations, with the development of more environmentally friendly lead-free PSCs and high-efficiency multi-junction cells. Overall, this review provides a critical evaluation of the advances, opportunities and challenges of PSCs.

Dielectric relaxation behavior of multi-walled carbon nanotube (MWCNT)-reinforced silicone elastomer nanocomposites has been studied as a function of filler loading in a wide frequency range (10 À1 -10 6 Hz). The effect of MWCNT loading on the real and imaginary parts of impedance is distinctly visible. The significant change in the impedance parameters on filler loading is explained on the basis of interfacial polarization in a heterogeneous medium and relaxation dynamics of polymer chains. The electrical modulus formalism has been used to investigate the conductivity and relaxation phenomena of the system. The frequency dependence of ac conductivity is explained using percolation theory. The existence of percolation phenomenon in the composites is discussed on the basis of electrical conductivity and morphology of the composites. The percolation threshold (as studied by electrical conductivity) occurs in the range of 4 phr of MWCNT loading. The scanning electron photomicrographs show agglomeration of the MWCNT above 4 phr concentration and formation of a continuous network structure.