Enhanced performance of triple-junction tandem organic solar cells due to the presence of plasmonic nanoparticles

Abstract

A triple-junction tandem organic solar cell (OSC) having polymer active materials, P3HT:PC70BM, Si-PCPDTBT:PC70BM, and PMDPP3T:PC70BM is presented. These active layer materials cover a 300 nm to 1000 nm broad solar spectrum and have minimally overlapping narrow absorption bands. The performance of the triple-junction tandem OSC was improved by introducing plasmonic nanospheres (NSs) over the top electrode of the OSC. The OSCs were modeled in finite-difference time-domain (FDTD) to optimize the performance of the NSs. Nanospheres of three plasmonic materials—gold (Au), silver (Ag), and aluminum (Al) were individually simulated over the top electrode of the OSCs. The NSs affect absorption in the active layer materials, around their respective plasmonic resonance peaks. The low-cost Al NSs enhance light trapping in the top and middle subcells, leading to a 14% improvement in overall short circuit current density (JSC) of the triple-junction tandem OSC in comparison with that of the reference OSC without any NSs. It is also observed that while the enhancement of the overall JSC of the triple-junction tandem OSC due to the Al NSs is greater than that due to the Ag NSs, the presence of Au NSs leads to a decrease in the overall JSC in comparison with that of the reference OSC.