Highly Efficient Nonfullerene Acceptor with Sulfonyl-Based Ending Groups

Abstract

Ending groups play a vital role in regulating the band gap and energy level of low-band gap nonfullerene acceptors (NFAs). In this work, a novel NFA, BTP-IS, is synthesized by adopting sulfonyl-based ending groups. Compared to the ketone counterpart BTP-IC, BTP-IS exhibits a red-shift in absorption spectra with lower lowest unoccupied molecular orbital level. More importantly, the BTP−IS-based organic solar cells with PM6 as donor present a high power conversion efficiency (PCE) of 12.79%, which is much higher than that of the BTP-IC device (PCE of 7.54%). The efficient charge transfer between the polymer donor and NFA acceptor, the balance charge transport, and the fine photoactive morphology bear on the effective exciton dissociation and charge collection in the BTP-IS device, which induces high short circuit current (J SC ) and fill factor (FF) values. This research has shed light on designing novel NFAs from the perspective of ending groups.

A novel naphthalene diimide-based conjugated polymer as an electron transport material for non-fullerene organic solar cells

“…The increase of electron mobility may weaken the excessive accumulation of carriers, which will help in reducing the charge recombination, thereby increasing J SC and FF. 58,60…”

Recent Progress in the Design of Fused-Ring Non-Fullerene Acceptors─Relations between Molecular Structure and Optical, Electronic, and Photovoltaic Properties

“…Exchanging the carbonyl unit at the INCN end groups of 7-144 with a sulfone group leads to 7-196 (BTP-IS). 210 In comparison, the sulfone lowers both energy levels and gives a slightly lower band gap than 7-144. Combined with PM6, the 7-196-based device shows lower V OC but higher J SC , FF, and PCE values, enhancing the efficiency from 7.…”

“…54 reason therefore can be the much higher electron mobility in the blend film of 7-196 compared to 7-144, as well as the more effective exciton dissociation and charge collection. 210 The exchange of the benzene unit of the INCN group with a [c]-thiophene ring leads to the structures 7-197 (Y10) 243 ). This study shows that asymmetric end group engineering may be an efficient way for enhancing the PCE.…”

“…However, P3HT/ 7-195 -based devices possess a similar V OC as solar cells with PM6/ 7-160 absorber layers, but all other parameters are much lower with an efficiency of 9.46%. Exchanging the carbonyl unit at the INCN end groups of 7-144 with a sulfone group leads to 7-196 (BTP-IS) . In comparison, the sulfone lowers both energy levels and gives a slightly lower band gap than 7-144 .…”

“…Combined with PM6, the 7-196 -based device shows lower V OC but higher J SC , FF, and PCE values, enhancing the efficiency from 7.54 to 12.8%. A reason therefore can be the much higher electron mobility in the blend film of 7-196 compared to 7-144 , as well as the more effective exciton dissociation and charge collection . The exchange of the benzene unit of the INCN group with a [ c ]-thiophene ring leads to the structures 7-197 (Y10) and 7-198 (BTCT-2Cl) with the latter having the same undecyl and ethylhexyl side chains as in 7-143 and 7-198 having additional chlorines on the acceptor units.…”