The ZnO/CsPbBr3 heterojunction interface often
has poor
chemical stability, resulting in the low photovoltaic efficiency of
the solar cell. Here, we reported a method to fabricate an electron
transport layer (ETL) using an Al element-doped ZnO (AZO) sol to improve
the interfacial defects of the ZnO/CsPbBr3 heterojunction.
The results showed that the interfacial defects first decreased and
then increased with the change of the Al element ratio from 0 to 10%.
The device had the least interfacial defects by 7% (atomic ratio)
Al doping into ZnO. A 1.27 V open-circuit voltage (V
OC) and 6.25% photoelectric conversion efficiency (PCE)
were achieved by 7% Al element doping into ZnO in a ZnO/CsPbBr3/carbon structure solar cell. Moreover, the interfacial defect
distribution and carrier recombination mechanism of the device were,
respectively, illustrated by a varying light intensity test and electrochemical
impedance spectroscopy. This work showed that an Al-doped ZnO film
prepared by a sol–gel method could significantly improve the
performance of solar cells.