Perovskite solar cells (PSCs) usually suffer from a hysteresis effect in current–voltage measurements,
which leads to an inaccurate estimation of the device e
fficiency. Although ion migration, charge trapping/
detrapping, and accumulation have been proposed as a b
asis for the hysteresis, the
origin of the hysteresis
has not been apparently unraveled. Herein we reporte
d a tunable hysteresis effect based uniquely on open-
circuit voltage variations in printable mesos
copic PSCs with a simplified triple-layer TiO
2
/ZrO
2
/carbon
architecture. The electrons are collected by the compact TiO
2
/mesoporous TiO
2
(c-TiO
2
/mp-TiO
2
)bilayer,
and the holes are collected by the carbon layer. By adj
usting the spray deposition cycles for the c-TiO
2
layer
andUV-ozonetreatment,weachievedhysteresis-norm
al, hysteresis-free, and hysteresis-inverted PSCs.
Such unique trends of tunable hysteresis are anal
yzed by considering the polarization of the TiO
2
/perovskite
interface, which can accumulate positive charges reversibly. Successfully tuning of the hysteresis effect
clarifies the critical importance of the c-TiO
2
/perovskite interface in controlling the hysteretic trends
observed, providing important insights towards the understanding of this rapidly developing photovoltaic
technology
