Effect of Polymer Side Chains on Charge Generation and Disorder in PBDTTPD Solar Cells

• DOI: 10.1021/acsami.5b09497
• Publication Date: 2015-11-17T13:39:57Z
• Authors: Iordania Constant...; Tzung-Han Lai; Erik D. Klump; Subhadip Goswami; Kirk S. Schanze; Franky So
• Keywords: Side chain; Moiety; Acceptor; Quantum Efficiency

The effect of polymer side chains on device performance was investigated for PBDT(EtHex)-TPD(Oct):PC70BM and PBDT(EtHex)-TPD(EtHex):PC70BM BHJ solar cells. Going from a linear chain the polymer's acceptor moiety to branched determined have negative impact overall efficiency, because significantly reduced short-circuit current (J(sc)) fill factor (FF) values. Sub-bandgap external quantum efficiency (EQE) transient photoluminescence (PL) measurements showed more-efficient carrier generation with chains, higher degree charge-transfer (CT) state delocalization, leading exciton dissociation. Furthermore, increase in π-π stacking distance disorder bulkier ethylhexyl were shown result lower hole mobility, bimolecular recombination, energetic disorder. use promote photogeneration, more-effective CT states favorable transport resulting improved cell performance.