The organic-inorganic hybrid lead halide perovskite has a bandgap 1.5 eV and VOC of this perovskite-based solar cell was much greater than that of a dye-sensitized solar cell, rendering this photovoltaic system promising for further investigations. In this lecture, both n-type and p-type perovskite solar cells will be introduced based on varied structural configurations of the devices. Typical n-type device has a structural configuration FTO/TiOx/TiO2/CH3NH3PbI3/Spiro-OMeTAD/Au whereas that of a p-type device is configured as ITO/PEDOT:PSS/CH3NH3PbI3/PCBM/Al. For n-type devices, varied mesoporous TiO2 nanostructures were applied to show the morphological effect of the scaffold on the device performance with a mesoscopic heterojuction; for p-type devices, varied additives were applied to control the formation morphology of the perovskite nanocrystals with a planar heterojunction. To understand the relaxation mechanism inside the perovskite solar cells, we carried out femtosecond optical gating (FOG) measurements for perovskite (CH3NH3PbI3) deposited on thin films of nanocrystalline TiO2, NiO and Al2O3 upon excitation at 450 nm. The emission transients of perovskite on semiconductor films were observed in the spectral region 650-810 nm. Measurements of power dependence on emission intensities vs excitation densities were also performed and an Auger-type energy transfer model was utilized to rationalize the observed relaxation dynamics. Photo-induced absorption spectra and nanosecond transient absorption kinetics were also performed to understand the electron-hole recombination rates responsible for the corresponding device performances.