  If charge carriers accumulate in the charge transport layer of a solar cell,
then the transient response of the electric field that originates from these
accumulated charges results in hysteresis in the current-voltage ($J$-$V$)
characteristics. While this mechanism was previously known, a theoretical model
to explain these $J$-$V$ characteristics has not been considered to date. We
derived an equivalent circuit from the proposed hysteresis mechanism. By
solving the equivalent circuit model, we were able to reproduce some of the
features of hysteresis in perovskite solar cells.
