Abstract:
: This study focuses on employing cuprous iodide (CuI) as a hole-transporting material
(HTM) in fabricating highly efficient perovskite solar cells (PSCs). The PSCs were made in air with
either CuI or 2,20
,7,70
-Tetrakis[N,N-di(4-methoxyphenyl)amino]-9,90
-spirobifluorene (spiro-OMeTAD)
as HTMs. A simple and novel pressing method was employed for incorporating CuI powder layer
between perovskite layer and Pt top-contact to fabricate devices with CuI, while spiro-OMeTAD
was spin-coated between perovskite layer and thermally evaporated Au top-contact to fabricate
devices with spiro-OMeTAD. Under illuminations of 100 mW/cm2 with an air mass (AM) 1.5 filter in
air, the average short-circuit current density (JSC) of the CuI devices was over 24 mA/cm2
, which is
marginally higher than that of spiro-OMeTAD devices. Higher JSC of the CuI devices can be attributed
to high hole-mobility of CuI that minimizes the electron-hole recombination. However, the average
power conversion efficiency (PCE) of the CuI devices were lower than that of spiro-OMeTAD devices
due to slightly lower open-circuit voltage (VOC) and fill factor (FF). This is probably due to surface
roughness of CuI powder. However, optimized devices with solvent-free powder pressed CuI as
HTM show a promising efficiency of over 8.0 % under illuminations of 1 sun (100 mW/cm2
) with an
air mass 1.5 filter in air, which is the highest among the reported efficiency values for PSCs fabricated
in an open environment with CuI as HTM.
