Alloy-like ternary polymer solar cells with over 17.2% efficiency

Ternary strategy has been considered as an efficient method to achieve high performance polymer solar cells(PSCs). A power conversion efficiency(PCE) of 17.22% is achieved in the optimized ternary PSCs with10 wt% MF1 in acceptors. The over 8% PCE improvement by employing ternary strategy is attributed to the simultaneously increased JSCof 25.68 mA cm^-2, VOCof 0.853 V and FF of 78.61% compared with Y6 based binary PSCs. The good compatibility of MF1 and Y6 can be confirmed from Raman mapping, contact angle,cyclic voltammetry and morphology, which is the prerequisite to form alloy-like state. Electron mobility in ternary active layers strongly depends on MF1 content in acceptors due to the different lowest unoccupied molecular orbital(LUMO) levels of Y6 and MF1, which can well explain the wave-like varied FF of ternary PSCs. The third-party certified PCE of 16.8% should be one of the highest values for single bulk heterojunction PSCs. This work provides sufficient references for selecting materials to achieve efficient ternary PSCs.

Semitransparent polymer solar cells with 12.37% efficiency and 18.6% average visible transmittance

A series of opaque and semitransparent polymer solar cells(PSCs)were fabricated with PM6:Y6 as active layers,and 100 nm Al or 1 nm Au/(20,15,10 nm)Ag layer as electrode,respectively.The power conversion efficiency(PCE)of opaque PSCs arrives to 15.83%based on the optimized active layer with a thickness of 100 nm,resulting from the well-balanced photon harvesting and charge collection.Meanwhile,the 100 nm PM6:Y6 blend film exhibits a 50.5%average visible transmittance(AVT),which has great potential in preparing efficient semitransparent PSCs.The semitransparent electrodes were fabricated with 1 nm Au and different thick Ag layers,exhibiting a relatively high transmittance in visible light range and relatively low transmittance in near infrared range.The PCE and AVT of the semitransparent PSCs can be adjusted from 14.20%to 12.37%and from 8.9%to 18.6%along with Ag layer thickness decreasing from 20 to 10 nm,respectively,which are impressive values among the reported semitransparent PSCs.

Over 16.7% efficiency of ternary organic photovoltaics by employing extra PC71BM as morphology regulator

Ternary organic photovoltaics(OPVs)are fabricated with PBDB-T-2 Cl:Y6(1:1.2,wt/wt)as the host system and extra PC71BM as the third component.The PBDB-T-2 Cl:Y6 based binary OPVs exhibit a power conversion efficiency(PCE)of 15.49%with a short circuit current(JSC)of 24.98 mA cm^-2,an open circuit voltage(VOC)of 0.868 V and a fill factor(FF)of 71.42%.A 16.71%PCE is obtained in the optimized ternary OPVs with PBDB-T-2 Cl:Y6:PC71BM(1:1.2:0.2,wt/wt)active layer,resulting from the synchronously improved JSC of 25.44 mA cm^-2,FF of 75.66%and the constant VOCof 0.868 V.The incorporated PC71BM may prefer to mix with Y6 to finely adjust phase separation,domain size and molecular arrangement in ternary active layers,which can be confirmed from the characterization on morphology,2 D grazing incidence small and wide-angle X-ray scattering,as well as Raman mapping.In addition,PC71BM may prefer to mix with Y6 to form efficient electron transport channels,which should be conducive to charge transport and collection in the optimized ternary OPVs.This work provides more insight into the underlying reasons of the third component on performance improvement of ternary OPVs,indicating ternary strategy should be an efficient method to optimize active layers for synchronously improving photon harvesting,exciton dissociation and charge transport,while keeping the simple cell fabrication technology.

Chloro-free synthesis of LiPF_(6)using the fluorine-oxygen exchange technique

A hydrogen fluoride-free and chloro-free method for synthesizing LiPF_(6) was developed.Employing CaF_(2) as the direct fluorinating reagent instead of hydrogen fluoride made it much safer and more environmentfriendly than conventional methods and reduced the metal residues in product owing to the relatively low-acid reaction conditions less corrosive to equipments.The use of P_(2)O_(5) as phosphorus source instead of traditionally employed PCl_(5) significantly reduced the chloro residue in product.Ca(H_(2)PO_(4))_(2),the only by-product of the process,could be easily converted into Ca_(3)(PO_(4))_(2),a best-selling chemical.The above advantages not only reduce the production costs by ca.20%,but also significantly improve the product purity.The fluorine-oxygen exchange reaction is a completely new technique for LiPF_(6) production and may bring about technological revolution in the related industry.