Organic–inorganic
hybrid perovskites have become the most
promising materials for the next generation of solar cells. However,
the low thermal and chemical stability of these materials represented
by CH3NH3PbI3 is the most challenging
issue, which ultimately affects the durability of devices. Therefore,
to fundamentally improve the stability of perovskite solar cells,
we need to explore more stable organic–inorganic perovskite
materials. Using superlattice structures is an attractive strategy
to expand the perovskite family and obtain excellent optoelectronic
materials. The stability and photoelectric properties of hybrid perovskites
can be improved by introducing a functional diamino cation. Therefore,
the superlattice structure, thermodynamic stability, electronic properties,
exciton properties, power conversion efficiency, and optical absorption
properties of (CsPbI3)
n
/PDAPbI4 (n = 1–4) and (MAPbI3)
n
/PDAPbI4 (n =
1–4) hybrid perovskites are calculated using the first-principles
method based on density functional theory. The PDA in the superlattices
is p-phenylenediamine. The results show that these
superlattices show good thermodynamic stability, and these superlattices
have direct band gaps and are tunable, with small effective masses
of electrons and holes. By increasing the coupling effect between
Pb–I inorganic layers, diamino organic cations become more
conducive to the carrier migration between Pb–I inorganic layers.
The charge densities of the maximum valence band state and the minimum
conduction band state are distributed in different regions of the
superlattice. It is shown that (MAPbI3)
n
/PDAPbI4 (n = 3 and 4) structures
are type II superlattices and the recombination rate of electron–hole
pairs is greatly reduced. These superlattices have good optical absorption
characteristics and high absorption coefficients in the range of solar
radiation, which can provide theoretical support for obtaining stable
and efficient perovskite optoelectronic devices. The power conversion
efficiencies of single-junction solar cells based on (CsPbI3)4/PDAPbI4 and (MAPbI3)4/PDAPbI4 perovskites are 22.87 and 21.02%, respectively.