Large active area inverted tandem polymer solar cell with high performance via insertion of subnano-scale silver layer

Abstract We propose the deposition of ultra-thin silver layer (in subnano-scale) between bottom subcell and the hole-transport sublayer in the interlayer (IL), poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), in the inverted tandem polymer solar cell (t-PSC) for improving the wettability of aqueous hole-transport interlayer on hydrophobic active layer so that the performance is significantly improved and larger active area is allowed. The inverted t-PSC is composed of bottom subcell (regioregular poly(3-hexylthiophene) (P3HT): indene-C 60 -bisadduct (ICBA)) and the top subcell (thieno[3,4-b]thiophene/benzodithiophene (PTB7) with [6,6]-phenyl C 71 -butyric acid methyl ester (PC 71 BM)) along with the IL, PEDOT:PSS/ZnO nanoparticles. For the small-area (0.03 cm 2 ) t-PSC, the power conversion efficiency (PCE) can be improved from 7.06% without Ag layer to 7.81% with depositing 0.5 nm Ag layer, and the device production yield from 40% (4 out of 10 devices) to near 100% (10 out of 10 devices), which can be ascribed to more efficient hole collection and reducing leakage current for the bottom subcell due to improvement of film forming of PEDOT:PSS. As the active area is increased to 1 cm 2 , a PCE of over 6% (6.11%) can also be achieved by this approach, which is much higher than that without such Ag layer (2.19%) by a factor of 2.78. The reported active area of inverted t-PSC is in the range 0.02–0.15 cm 2 ; while the present method allows an inverted t-PSC to enlarge its active area to 1 cm 2 , yet the PCE can maintain over 6%.