  Thin films of pure and self-deficient calcium titanites i.e., CaTiO$_3$,
Ca$_{1-\alpha}$TiO$_3$, CaTi$_{1-\beta}$O$_3$ and CaTiO$_{3-\gamma}$ have been
deposited on ITO substrate using dip coating method. X-ray diffraction and
Scanning electron Microscopy (SEM) analysis confirm the structural and
morphology of all deposited thin films. Photocurrent measurement has been done,
and it is observed that during the incidence of UV light on the as-prepared
device (i.e., in the "ON" state), a significant increase in photocurrent (IUV)
at zero voltage was observed in case of O deficient CaTiO$_3$, while in case of
Ti and Ca deficient thin films smaller values of photocurrents were seen.
Responsivity and detectivity of deposited thin films of all self-deficient
CaTiO3 were found to be maximum in the UV region while they also showed smaller
contributions in the visible range possibly due to the presence of
self-deficiency. The self-deficient sample exhibits lower resistance (higher
recombination rate) than the pure sample at low voltage, but at higher voltage,
it is almost identical. Furthermore, theoretical calculations have been
performed using the first-principles density-functional theory to validate the
experimental findings on self-deficient CaTiO$_3$. Incident-photon-to-current
efficiency (IPCE) and current density have also been measured for all deficient
CaTiO$_3$ samples. Maximum IPCE have been found in the range 25%-28% for Ti and
O deficient samples in the UV range (280- 400 nm). We argue that
first-principles DFT calculations combined with the experimental measurements
on self-deficient CaTiO$_3$ thin films offer a reliable way to enhance the
performance of perovskite-based solar devices.
