One of the most important factors that limits the efficiencies of bulk‐heterojunction organic solar cells (OSCs) is the modest open‐circuit voltage (Voc) due to their large voltage loss (Vloss) caused by significant nonradiative recombination loss. To boost the performance of OSCs toward their theoretical limit, developing high‐performance donor: acceptor systems featuring low Vloss with suppressed nonradiative recombination losses (<0.30 V) is desired. Herein, high performance OSCs based on a polymer donor benzodithiophene‐difluorobenzoxadiazole‐2‐decyltetradecyl (BDT‐ffBX‐DT) and perylenediimide‐based acceptors (PDI dimer with spirofluorene linker (SFPDI), PDI4, and PDI6) are reported which offer a high power conversion efficiency (PCE) of 7.5%, 56% external quantum efficiency associated with very high Voc (>1.10 V) and low Vloss (<0.60 V). A high Voc up to 1.23 V is achieved, which is among the highest values reported for OSCs with a PCE beyond 6%, to date. These attractive results are benefit from the suppressed nonradiative recombination voltage loss, which is as low as 0.20 V. This value is the lowest value for OSCs so far and is comparable to high performance crystalline silicon and perovskite solar cells. These results show that OSCs have the potential to achieve comparable Voc and voltage loss as inorganic photovoltaic technologies.
Despite
the great advances in the synthesis of diverse nonplanar
graphenoids, investigations into the relationship between structural
features and intermolecular interactions still present significant
challenges. Herein, the novel nonplanar graphenoid structure, corannurylene
pentapetalae (CRP), obtained via bottom-up syntheses of hybridization
between perylene diimide (PDI) planar fragments and a corannulene
curved core, is presented. Single crystal studies reveal a D
5-symmetric as well as a C
2-symmetric graphenoid corannurylene pentapetalae. The D
5-symmetric structure has a unique honeycomb
lattice with two chiral honeycomb layers alternately stacked, whereas
the C
2-symmetric CRP forms dimer units
via π–π stacking. Transistor devices demonstrate
that, without any π–π stacking, the honeycomb lattice
of the D
5-symmetric CRP has the potential
to also facilitate electron transport.
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