Fabrication and characterization of ZnTPP:PCBM bulk heterojunction (BHJ) solar cells

Bulk heterojunction (BHJ) solar cells were fabricated based on blended films of a porphyrin derivative 5,10,15,20-Tetraphenyl-21H,23H-porphine zinc (ZnTPP) and a fullerene derivative [6,6]-phenyl-C61 butyric acid methyl ester (PCBM) as the active layer. The ZnTTP:PCBM BHJ solar cells were fabricated by spin-casting of the blended layer. The weight ratios of ZnTPP and PCBM were varied from 1:1 to 0:10. The electronic and optical properties of each cell were investigated. Optical density (OD) of the blended film for each cell was extracted from its reflection and transmission curves. OD and average absorption coefficients of the active materials were used to determine film thicknesses. Absorption spectra of each component material were compared with the spectra of the blended films. Current density–Voltage (J–V) characteristics were recorded under dark as well as under the illumination of AM 1.5G (1 sun) solar spectrum. The BHJ solar cell with ZnTPP:PCBM ratio of 1:9 showed the best performance . The values of RR, VOC , JSC , FF and η for these ratios were 106.3, 0.4 V, 1.316 mA/cm2, 0.4 and 0.21%, respectively. The cross-section of this device using SEM was also examined.

► ZnTPP:PCBM bulk heterojunction (BHJ) solar cells fabricated and characterized for optical and electronic properties.
► ZnTPP (donor) and PCBM (acceptor) ratios in the BHJ solar cells varied to find ratio for best performance.
► ZnTPP:PCBM BHJ solar cells showed the best efficiency (0.21%) at ZnTPP to PCBM weight ratio of 1:9.
► Absorption spectra of blended film compared with the absorption spectra of films of individual components.
► IPCE spectra of the solar cells at different donor–acceptor ratios recorded.