A Dispiro‐Type Fluorene‐Indenofluorene‐Centered Hole Transporting Material for Efficient Planar Perovskite Solar Cells. Issue 7 (25th April 2018) - Yu, Wei
Abstract : A novel dispiro[fluorene‐indenofluorene]‐based compound, dispiro‐OBuTAD (shortened as Dispiro) with a 3π‐2 spiro core is designed and synthesized as a hole transporting material (HTM) for perovskite solar cells (PSCs). The Dispiro with two spiro centers shows rigid ladder‐type structure, great steric hindrance, and reduced molecular symmetry, which favor good thermal stability and homogeneous film morphology. Devices with Dispiro as HTM afford a high power conversion efficiency amounting to 18.46% in MAPbI3 ‐based planar PSCs, which is higher than the value (17.82%) of the well‐known spiro‐OMeTAD‐based devices. The Dispiro can form amorphous homogeneous films with improved hole mobility and enhanced hole extraction from perovskite to HTM, resulting in high performance of Dispiro‐based PSCs. This work provides the first example of fluorene‐indenofluorene‐centered dispiro‐type HTM for PSC application, suggesting a promising approach to design HTMs by increasing the spiro center. Abstract : A novel fluorene‐indenofluorene‐based HTM, Dispiro‐OBuTAD (Dispiro), is designed and synthesized. The Dispiro with two spiro centers exhibits a rigid ladder‐type architecture, showing reduced molecular symmetry and good film‐forming property. The Dispiro‐based PSCs provide a PCE of 18.5%, higher than that (17.8%) of well‐known spiro‐OMeTAD‐based devices, demonstrating that increasing the spiro center is a promising designing principle to develop excellent HTMs for high‐performance PSCs.