This work reports the design of a wavelength sensor composed of two
identical perovskite (FA0.85Cs0.15PbI3) photodetectors (PDs) that are capable
of discriminating incident wavelength in a quantitative way. Due to strong
wavelength-dependent absorption coefficient, the penetration depth of the
photons in the FA0.85Cs0.15PbI3 nanofilms increases with the increasing wavelength,
leading to a gradual decrease of photo-generated current for PD1, but
an increase of photocurrent in PD2, according to the theoretical simulation
of Technology Computer Aided Design. This special evolution of photo-generated
current as a function of wavelength facilitates the quantitative determination
of the wavelength since the current ratio of both PDs monotonously
decreases with the increase of wavelength from 265 to 810 nm. The average
absolute error and the average relative error are estimated to be 7.6 nm
and 1.68%, respectively, which are much better than other semiconductors
materials-based wavelength sensors previously reported. It is believed that
the present perovskite film-based wavelength sensor will have potential application
in the future color/spectrum optoelectronic devices.