3D asymmetric carbozole hole transporting materials for perovskite solar cells

Carbazole compounds are p-type hole-transporting materials (HTMs) useful for perovskite solar cells (PSCs). In this work, we developed a new class of carbazol based HTMs; non-fused 3-D asymmetric structures (S14 and S12) as HTM of PSCs. To the best of our knowledge, there is no report on non-fused HTMs with a high glass transition temperature (T-g = 165 degrees C), which reduces crystallization and suppresses grain boundaries in glassy film, resulting in long-term durability. Experimental results show that tuning the carbazole moiety in S14 structure has a constructive influence on geometrical alignment, hole mobility, hydrophobicity, stability as well as efficiency. The resultant power conversion efficiency (PCE) of devices were 15.31% and 11.85% for S14 and S12, respectively. Cell efficiency decreases during the first day for all devices. But after this time, the cell efficiency of the device fabricated with S14 remains constant until 1000 h at atmospheric condition without encapsulation while for devices fabricated by S12 and Spiro-OMeTAD the cell efficiency decreases to 75% and 69%.