Enhanced Charge Separation in Ternary P3HT/PCBM/CuInS₂ Nanocrystals Hybrid Solar Cells

Aurélie Lefrançois (1) , Beata Luszczynska (2) , Brigitte Pepin-Donat (1) , Christian Lombard (1) , Benjamin Bouthinon (3) , Jean-Marie Verilhac (3) , Marina Gromova (4) , Jérôme Faure-Vincent (1) , Stéphanie Pouget (5) , Frédéric Chandezon (1) , Saïd Sadki (1) , Peter Reiss (1)

1 LEMOH - Laboratoire d'Electronique Moléculaire Organique et Hybride
2 Łódź University of Technology
3 LITEN - Laboratoire d'Innovation pour les Technologies des Energies Nouvelles et les nanomatériaux
4 RM - Magnetic Resonance
5 SGX - Service Général des Rayons X

Geminate recombination of bound polaron pairs at the donor/acceptor interface is one of the major loss mechanisms in organic bulk heterojunction solar cells. One way to overcome Coulomb attraction between opposite charge carriers and to achieve their full dissociation is the introduction of high dielectric permittivity materials such as nanoparticles of narrow band gap semiconductors. We selected CuInS2 nanocrystals of 7.4 nm size, which present intermediate energy levels with respect to poly(3-hexylthiophene) (P3HT) and Phenyl-C61-butyric acid methyl ester (PCBM). Efficient charge transfer from P3HT to nanocrystals takes place as evidenced by light-induced electron spin resonance. Charge transfer between nanocrystals and PCBM only occurs after replacing bulky dodecanethiol (DDT) surface ligands with shorter 1,2-ethylhexanethiol (EHT) ligands. Solar cells containing in the active layer a ternary blend of P3HT:PCBM:CuInS2-EHT nanocrystals in 1:1:0.5 mass ratio show strongly improved short circuit current density and a higher fill factor with respect to the P3HT:PCBM reference device. Complementary measurements of the absorption properties, external quantum efficiency and charge carrier mobility indicate that enhanced charge separation in the ternary blend is at the origin of the observed behavior. The same trend is observed for blends using the glassy polymer poly(triarylamine) (PTAA).

Domaines: Chimie

Aurélie Lefrançois, Beata Luszczynska, Brigitte Pepin-Donat, Christian Lombard, Benjamin Bouthinon, et al.. Enhanced Charge Separation in Ternary P3HT/PCBM/CuInS₂ Nanocrystals Hybrid Solar Cells. Scientific Reports, 2015, 5, pp.7768. ⟨10.1038/srep07768⟩. ⟨hal-01502561⟩