Applications of hybrid organic-inorganic metal halide perovskite thin film as a hole transport layer in CdTe thin film solar cells

We fabricate and characterize methylammonium lead halide perovskite film as a novel back contact to CdTe thin film solar cells. We prepare a ~500 nm perovskite film directly on a CdCl
₂
-activated and Cu-doped CdTe polycrystalline film, and complete the device with Au back contact. Results of this novel back contact are compared with the performance of a Cu/Au back contact. Our investigation shows that incorporation of a thin perovskite layer before the back contact metallization reduces the back contact barrier effect, improving both FF and VOC of the solar cells. These improvements are consistent with improved passivation and a lower or negligible valence band offset between CdTe and the perovskite, especially with the incorporation of the Br in perovskite. Our best device shows FF improvement by ~3% with the highest FF of 78%, and solar cell efficiency increases by 5% when MAPb(I
_0.7
Br
_0.3
)
₃
is used as a hole transfer layer.