  Pyroelectric and photovoltaic effects are vital in cutting-edge thermal
imaging, infrared sensors, thermal and solar energy harvesting. Recent advances
revealed the great potential of the bulk photovoltaic effect in two-dimensional
(2D) semiconductor-ferroelectric materials to enable reconfigurable p-n
junction operation with the potential to surpass the Shockley-Queiseer limit.
Moreover, the extremely low thickness, high thermal conductivity, dangling
bonds free interface, and room-temperature stable ferroelectricity down to a
single monolayer endow 2D ferroelectrics with a superior pyroelectric figure of
merit. Herein, we performed direct pyroelectric measurements of 2D
$\alpha$-In$_2$Se$_3$ under dark and light conditions. The results reveal a
gigantic pyroelectric coefficient of 30.7 mC/m$^2$K and a figure of merit of
135.9 m$^2$/C. In addition, we perform temperature-dependent short-circuit
photovoltaic response measurements in which the excess photocurrent is
modulated in proportion with the temperature variations due to the induced
in-plane potential variations. Consequently, the discovered
pyroelectric-photovoltaic effect allows the combination of direct temperature
(photovoltaic) and temperature-derivative (pyroelectric) sensing. Finally, we
utilized the intercoupled ferroelectricity of In$_2$Se$_3$ to realize a
non-volatile, self-powered photovoltaic memory operation, demonstrating a
stable short-circuit current switching with a decent 103 ON-OFF ratio. The
coupled pyroelectric-photovoltaic effect, along with reconfigurable
photocurrent, pave the way for a novel monolithic device technology with
integrated thermal and optical response, in-memory logic and energy harvesting.
