Heralded as a major scientific breakthrough of 2013, organic/inorganic lead halide perovskite solar cells have ushered in a new era of renewed efforts at increasing the efficiency and lowering the cost of solar energy. As a potential game changer in the mix of technologies for alternate energy, it has emerged from a modest beginning in 2012 to efficiencies being claimed at 20.1% in a span of just two years. This remarkable progress, encouraging at one end, also points to the possibility that the potential may still be far from being fully realized. With greater insight into the photophysics involved and optimization of materials and methods, this technology stands to match or even exceed the efficiencies for single crystal silicon solar cells. With thin film solution processability, applicability to flexible substrates, and being free of liquid electrolyte, this technology combines the benefits of Dye Sensitized Solar Cells (DSSCs), Organic Photovoltaics (OPVs), and thin film solar cells. In this review we present a brief historic perspective to this development, take a cognizance of the current state of the art, and highlight challenges and the opportunities.

We have used liquid exfoliation of hexagonal Boron-Nitride (BN) to prepare composites of BN nanosheets of three different sizes in polyvinylchloride matrices. These composites show low levels of reinforcement, consistent with poor alignment of the nanosheets as-described by a modified version of Halpin–Tsai theory. However, drawing of the composites to 300% strain results in a considerable increase in mechanical properties with the maximum composite modulus and strength both ∼×3 higher than that of the pristine polymer. In addition, the rate of increase of modulus with BN volume fraction was up to 3-fold larger than for the unstrained composites. This is higher than can be explained by drawing-induced alignment using Halpin–Tsai theory. However, the data was consistent with a combination of alignment and strain-induced de-aggregation of BN multilayers.