Enhancement of efficiency of a conducting polymer P3HT:CdSe/ZnS quantum dots hybrid solar cell by adding single walled carbon nanotube for transporting photogenerated electrons

Abstract

Hybrid solar cells consisting of a composite of poly (3-hexylthiophene) (P3HT), single walled carbon nanotube (SWCNT), and cadmium selenide/zinc sulphide (CdSe/ZnS) coreshell quantum dots (QDs) have been fabricated in the present work. The bulk hetrojunction has been formed from the bilayer of P3HT:SWCNT composite and QDs using inter-diffusion process. Due to low percolation limit and high conductivity of SWCNT, the photo-generated electrons are collected at the electrode very fast (within few femto-seconds) enhancing the efficiency of the solar cell. The absorption measurements on the composite film show that the addition of SWCNT in the hybrid structure increases the absorption coefficient in the near infrared region and also makes the spectrum wider as compared to that of P3HT. The photoluminescence (PL) measurements show that the PL of hybrid P3HT, SWCNT, and QDs is quenched about ∼15 times as compared to that of P3HT film. This shows that a significant charge transfer of electrons occurs through SWCNT to the electrode. The morphology of P3HT:SWCNT:CdSe/ZnS was observed using atomic force microscopy. With this approach, we have been able to achieve power conversion efficiency of 5.4% using a standard solar simulator with an irradiance of 100 mW/cm2. © 2013 AIP Publishing LLC.