In
our day-to-day lives, advances in lightweight and flexible photovoltaics
will promote a new generation of soft electronics and machines requiring
high power-per-weight. Ultrathin flexible perovskite solar cells (F-PSCs)
with high power-per-weight have displayed a unique potential for specific
applications where lower weight, higher flexibility, and conformability
are indispensable. This Review highlights the recent progress and
practical applications of ultrathin and lightweight F-PSCs and demonstrates
the routes toward enhanced device efficiency and improved mechanical
and environmental stability concerning the choice of flexible substrates
and the development of high-performance functional layers and flexible
transparent electrodes. The fabrication technologies for mass production
of efficient F-PSCs at large scale are then summarized, including
continuous roll-to-roll methods integrated with low-temperature process.
Furthermore, the practical applications focused on self-powered wearable
electronic devices, solar-powered miniature unmanned aerial vehicles,
and even solar modules operating in near-space are elaborated. Finally,
the current challenging issues and future perspective are discussed,
aiming to promote more extensive applications and commercialization
processes for lightweight F-PSCs.