• Energy Research

Binary additives synergistically boost the power conversion efficiency of all-polymer solar cells up to 3.45%. The nonvolatile additive PDI-2DTT suppresses aggregation of the acceptor PPDIDTT and enhances donor/acceptor mixing, while the additive DIO facilitates aggregation and crystallization of the donor PBDTTT-C-T as well as improves phase separation. Combination of DIO and PDI-2DTT leads to suitable phase separation and improved and balanced charge transport, which is beneficial to efficiency enhancement.

Abstract New series of thieno[3,4-c]pyrrole-4,6-dione(TPD)-based small molecules with donor–acceptor–donor structure were synthesized by palladium(0)-catalyzed Stille coupling reaction. The thermal, electrochemical, optical, charge transport, and photovoltaic properties of these small molecules were examined. These molecules exhibit strong absorption at 460–490 nm and low HOMO levels (−5.26 to −5.34 eV). Field-effect hole mobilities of these molecules are 0.8–1.3×10 −3 cm 2 V −1 s −1 . Solution processed bulk heterojunction organic solar cells based on the blends of these molecule donors and PC 71 BM acceptor exhibit power conversion efficiencies as high as 3.31% under AM1.5, 100 mW cm −2 .

AbstractRecently, research on nonfullerene acceptors in organic solar cells has gradually become a hot topic due to such superior characteristics of light absorption and energy‐level‐convenient manipulation, multiformity of the photoactive material structures, as well as the extensive area in production compared to the fullerene derivatives. However, the nonfullerene acceptors evolved slowly before 2012 and, as a matter of fact, the power conversion efficiency values could only bear 2.0%. Strikingly, nonfullerene acceptors have developed at a fast pace since 2013, with the best device performance of 13.1% now. In this review, recent research progress on nonfullerene acceptors, including small molecules and polymers, are sorted and summarized on the basis of the different characteristics.

NSFC [61072014, 51103164]; National Program on Key Basic Research Project (973 Program); Ministry of Science and Technology of China; Chinese Academy of Sciences; Minjiang Scholar Distinguished Professorship Program through Xiamen University of China; Specialized Research Fund for the Doctoral Program of Higher Education [2009012112002, 20100121120026]

Inverted all polymer solar cells based on a blend of a perylene diimide based polymer acceptor and a dithienosilole based polymer donor were fabricated from small area devices to roll-to-roll (R2R) coated and printed large area modules. The device performance was successfully optimized by using solvent additive to tune the phase separation. By adding 2% chloronaphthalene as solvent additive for small area (0.25 cm2) devices, a power conversion efficiency (PCE) up to 0.63% was achieved for inverted geometry, higher than that (0.39%) of conventional geometry. This polymer blend showed excellent solution processibility and R2R coated and printed large area (4.2 cm2) solar cells exhibited a PCE of 0.20%.