CH3NH3PbI3 crystal orientation and photovoltaic performance of planar heterojunction perovskite solar cells

- We fabricated highly oriented CH3NH3PbI3 crystals with two different orientations.
- The crystal orientation of perovskite is directly related to PCE.
- PCE difference is interpreted by the charge transfer lifetime.
- Strong hysteresisis interpreted in terms of slow and imbalanced charge transfer.

The effect of crystal orientation of CH3NH3PbI3 on photovoltaic properties has rarely been studied due to the lack of method to fabricate perovskite films with well-controlled crystal orientation in specific direction. Here, we have controlled the orientation of CH3NH3PbI3 crystal by changing organic precursors (CH3NH3I and CH3NH3Cl) and successfully fabricated highly oriented CH3NH3PbI3 crystals with two different orientations to the substrate. When we investigated the effect of crystal orientation on photovoltaic performance using the films with two different crystal orientations, we have realized that the crystal orientation of perovskite is directly related to power conversion efficiency (PCE). The PCE difference due to different crystal orientation is interpreted by the charge transfer lifetime. Faster charge transfer from perovskite layer to charge transport layer exhibits higher JSC and PCE.

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