D-π-D molecular semiconductors for perovskite solar cells: the superior role of helical planar π-linkers
Controlling the mode of molecular packing and the size of molecular aggregates is of fundamental importance for high-performance charge transport materials in next-generation optoelectronic devices. To clarify the peculiar role of helicene as a kernel block in the exploration of unconventional organ...
Gespeichert in:
Veröffentlicht in: | Chemical science (Cambridge) 2020-04, Vol.11 (13), p.3418-3426 |
---|---|
Hauptverfasser: | , , , , , , |
Format: | Artikel |
Sprache: | eng |
Online-Zugang: | Volltext |
Tags: |
Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
|
Zusammenfassung: | Controlling the mode of molecular packing and the size of molecular aggregates is of fundamental importance for high-performance charge transport materials in next-generation optoelectronic devices. To clarify the peculiar role of helicene as a kernel block in the exploration of unconventional organic semiconductors, in this work thia[5]helicene (T5H) is doubly aminated with electron-donating dimethoxydiphenylamine to afford T5H-OMeDPA, which is systematically compared with its perylothiophene (PET) congener (PET-OMeDPA). On the basis of the quantum theory of atoms in molecules and energy decomposition analysis of single crystals, it is surprisingly found that while π-π stacking of planar PET is stronger than that of helical T5H, this desirable effect for the charge transport of organic semiconductors is completely lost for donor-π-donor (D-π-D) type PET-OMeDPA but is retained for T5H-OMeDPA to a large extent. Consequently, the T5H-OMeDPA single-crystal presents about 5 times higher theoretical hole-mobility than PET-OMeDPA. More critically, the solution-processed racemic glassy film of T5H-OMeDPA displays a 3 times higher hole-mobility in comparison with the PET-OMeDPA counterpart, due to a larger domain of molecular aggregates. With respect to PET-OMeDPA, there is a weaker electronic coupling of helical T5H-OMeDPA with perovskites, leading to reduced interfacial charge recombination. Due to reduced transport resistance and enhanced recombination resistance, perovskite solar cells with T5H-OMeDPA exhibit a power conversion efficiency of 21.1%, higher than 19.8% with PET-OMeDPA and 20.6% with the spiro-OMeTAD control.
A thia[5]helicene based molecular semiconductor maintains π-π stacking, ensuring a large domain of molecular aggregates and a high hole mobility. |
---|---|
ISSN: | 2041-6520 2041-6539 |
DOI: | 10.1039/d0sc00362j |