Yongfang’s new NIR acceptor pushes the bandgap of OPV towards 1.2 eV and enables well performing tandem cells

Yongfang extended the pi-conjugation of Y6 by inserting a double bond between the central core and end groups and pushed the optical bandgap to 1.21 eV (BTPV-4F). The single-junction devices based on this novel acceptor achieved a short-circuit current density of 28.9 mA cm−2, and provide ideal conditions for current matching in tandems. The resulting tandem devices reached a high power conversion efficiency beyond 16 % (16.4 % uncertified) and exhibited as well good photostability. Very curious to find out what happens when introducing further double bonds into these molecules – achieving bandgaps comparable to the one of silicon appears to be within reach!