In this review article, we have given an overview of the historical
progress in perovskite solar cells and revisited the
fundamentals of organometal halide perovskite materials
from a viewpoint of optical absorption and charge transport
properties. Photoluminescence and impedance analysis
were described to be important tools which characterized the
charge separation, carrier transport, recombination, and diffusion
length in perovskite solar cells. Moreover, the correlation
between dielectric properties and the chemical bonding
nature in ionic crystals with molecular organic ions was also
discussed, which is also of great importance to understand
the photovoltaic properties of organometal halide perovskite
materials. Fabrication methods, including solution and
vacuum processes, were shown to influence crystal growth
and the morphologies of perovskite materials, thereby
impacting on the resultant energy conversion efficiency. Also,
recent progress underlying solution engineering exhibited
the capability of controlling the morphology of perovskite
materials for maximizing the energy conversion efficiency.
In particular, the potential of perovskite solar cells for use as
flexible solar cells was discussed in terms of low temperature
processing (below ∼150 °C), all-solid-state thin film nature,
and high efficiency. The flexible perovskite solar cell showed
an extraordinary bending durable property, fairly suitable for
being used as a power solution for future wearable devices.