Hybrid Solar Cells Based on Blends of CdSe Nanorods and Poly(3-alkylthiophene) Nanofibers

The influence of the polymer self-organization in poly(3-alkylthiophene):CdSe nanorod (NR) hybrid solar cells is investigated. The solvent used for the spin casting of the hybrid thin films has a strong influence on the device characteristics. Using solar cells of 28-mm active surface, the power conversion efficiency (PCE) was below 0.2% for blends deposited from chloroform, while values of 1.4%-1.6% have been achieved with chlorobenzene (CB) and o -dichlorobenzene (ODCB) under air mass (AM) 1.5 conditions (100 mW/cm). The slower film growth in the case of the higher boiling point solvents (CB and ODCB) allows the better self-organization of the polymer phase, improving the charge carrier mobility. Subsequently, we report for the first time the use of preformed poly(3-alkylthiophene) nanofibers (NFs) in hybrid solar cells with CdSe NRs, yielding a PCE of 1%. NFs prepared from poly(3-butylthiophene) resulted in a better device performance than those from poly(3-hexylthiophene). The obtained solar cells exhibit an interpenetrated 3-D network of interconnected NFs and small CdSe NR aggregates, providing efficient pathways for electron and hole transport in the hybrid film.