In Situ Growth of Metal Sulfide Nanocrystals in Poly(3-hexylthiophene): [6,6]-Phenyl C61-Butyric Acid Methyl Ester Films for Inverted Hybrid Solar Cells with Enhanced Photocurrent

Abstract

It has been reported that the performance of bulk heterojunction organic solar cells can be improved by incorporation of nano-heterostructures of metals, semiconductors, and dielectric materials in the active layer. In this manuscript, CdS or Sb2S3 nanocrystals were in situ generated inside the poly(3-hexylthiophene): [6,6]-phenyl C61-butyric acid (P3HT:PC61BM) system by randomly mixing P3HT and PC61BM in the presence of cadmium or antimony xanthate precursor. Hybrid solar cells (HSCs) with the configurations of tin-doped indium oxide substrate (ITO)/CdS interface layer/P3HT:PC61BM: x wt.% CdS/MoO3/Ag and ITO/CdS interface layer /P3HT:PC61BM: x wt.% Sb2S3/MoO3/Ag were fabricated. Hybrid active layers (P3HT:PC61BM: x wt.% CdS or P3HT:PC61BM: x wt.% Sb2S3) were formed completely by thermally annealing the film resulting in the decomposition of the cadmium or antimony xanthate precursor to CdS or Sb2S3 nanocrystals, respectively. The effects of x wt.% CdS (or Sb2S3) nanocrystals on the performance of the HSCs were studied. From UV–Vis absorption, hole mobilities, and surface morphological characterizations, it has been proved that incorporation of 3 wt.% CdS (or Sb2S3) nanocrystals in the active layer of P3HT:PC61BM-based solar cells improved the optical absorption, the hole mobility, and surface roughness in comparison with P3HT:PC61BM-based solar cells, thus resulting in the improved power conversion efficiencies (PCEs) of the devices.