Improved ternary organic solar cells by fluorene-diketopyrrolopyrrole polymer on the fullerene and non-fullerene active layers

Herein, two types of ternary organic solar cells (TOSCs) were implemented by adding a donor-acceptor polymer derived from fluorene and diketopyrrolopyrrole (PFDPP-1) as a second electro-donor component. For the first type of cells, poly(3-hexylthiophene) P3HT and the fullerene PC71BM were used. For these devices, a maximum power conversion efficiency (PCE) of 3.78% was achieved by adding 10% of PFDPP-1, while for the binary cells, 3.29% was obtained. For the second type of TOSCs, PBDB-T polymer was used as the electron donor, and the non-fullerene molecule ITIC as the electro-acceptor. By adding 2 wt% of the third component, a PCE of 9.10% was reached, while forbinary devices, PCE was 8.03%. The effective energy level offset led by PFDPP-1 between the polymeric donor and acceptor materials, as well as itscharge cascade effect, mainly contributed to an enhanced short circuit current density (Jsc) and thus to overall better photovoltaic performance. TOSCs fabrication and tests were carried out under normal atmosphere conditions by using Field's Metal (FM), as the top electrode, deposited at a regular atmosphere above 90 & DEG;C by drop casting.