Polymeric Hole‐Selective Contact for Crystalline Silicon Solar Cells

Carrier‐selective contacts based on inorganic materials (e.g., silicon layers and metal oxides) have been intensively investigated for efficient crystalline silicon ( c ‐Si) photovoltaics. Compared to the vacuum deposition process for inorganic films, organic semiconductors offer a simplified and low‐cost processing. Herein, solution‐processed poly[bis(4‐phenyl) (2,4,6‐trimethylphenyl) amine] (PTAA) is developed as hole‐selective contact for c ‐Si solar cells. PTAA exhibits a suitable band alignment with p‐type c ‐Si, featuring a small valence band offset (≈0.1 eV) and a large conduction band offset (≈2.2 eV) for effective electron blocking. PTAA combined with Al 2 O 3 passivation interlayer is demonstrated to simultaneously offer a low contact resistivity (36.5 mΩ cm 2 ) and a moderate surface passivation (implied open‐circuit voltage 635.6 mV) on p‐type c ‐Si surface. By the implementation of a full‐area hole‐selective Al 2 O 3 /PTAA rear contact, a champion efficiency of 20.2% is achieved on the hybrid c ‐Si solar cells. Herein, a guiding principle for future research on polymeric carrier‐selective contact for c ‐Si solar cells is provided.