We propose that 1 + 1 + 1 triple-junction solar cells can provide an increased efficiency, as well as a higher open circuit voltage, compared to tandem solar cells.

A high-performance semitransparent tandem solar cell that uses solutionprocessed graphene mesh and laminated Ag NW as a transparent anode and cathode, respectively, is demonstrated. The laminated top electrode can be deposited without causing any damage to the underneath organic solar cells. Power conversion effi ciencies of 8.02% and 6.47% are obtained when the light is projected from the solution-processed graphene mesh and laminated AgNW, respectively. The performance of the tandem cell is found to be comparable to a tandem solar cell fabricated using commercially available indium tin oxide. These fi ndings offer a high-performance device and open a new pathway in searching for a potential replacement to the frequently used transparent conducting electrodes.

A power conversion effi ciency of up to 8.91% is obtained for a solution-processed polymer tandem solar cells based on a large-bandgap polymer, poly(4,4-dioctyldithieno(3,2-b:2′,3′-d)silole)-2,6-diyl-alt -(2,1,3benzothiadiazole)-4,7-diyl) with a polymeric interconnecting layer to electrically connect the front and rear subcells, demonstrating that proper device and interface engineering are can improve the performance of polymer tandem solar cells.

We demonstrated the inverted solution processed tandem polymer solar cells, in which transparent pH-neutral poly(3,4-ethylenedioxylenethiophene)-polystylene sulfonic acid (PEDOT:PSS) and lithium zinc oxide layers were used as a recombination layer. We have used poly(di(2-ethylhexyloxy)benzo[1,2-b:4,5-b']dithiophene-co-octylthieno[3,4-c]pyrrole-4,6-dione):[6,6]-phenyl-C61 butyric acid methyl ester (PBDTTPD:PC61BM) and poly[(4,4'-bis(2-ethylhexyl)dithieno[3,2-b:2',3'-d] silole)-2,6-diyl-alt-(2,1,3-benzothiadiazole)-4,7-diyl]:[6,6]-phenyl-C70 butyric acid methyl ester (PSBTBT:PC70BM) as the active layers for front and rear subcells, respectively. The pH-neutral PEDOT:PSS/LZO serves as an electron- and hole-collecting and recombination layer. Our tandem solar cells showed a high open circuit voltage (Voc) of 1.54 V, a short circuit current density (Jsc) of 7.55 mA/cm(2), and a fill factor (FF) of 64.79% along with the power conversion efficiency of 7.53%. The Voc value of our tandem solar cells is an ideal summation of Voc values from front and rear subcells.