Effect of Carbon Nanotubes on the performance of Perovskite Solar Cells

Perovskite solar cells (PSCs) made with metal halide are affordable and can give better efficiency values than older versions but their low efficiency values is still a concern.  Two Perovskite solar cells were fabricated and one had Multi wall Carbon nanotube (MWCNT) in its design. The effect of the Multi-wall Carbon nanotube (MWCNT) on their performance and power conversion were studied. MWCNT and m-TiO2 materials were characterised using UV-vis spectroscopy and their optical energy band gap  values were obtained. The TiO2 showed a prominent peak at 319 nm with absorbance 0.5 and its optical energy bandgap  of 2.59 eV falls in the visible region showing it is a clean energy source with implications for solar energy conversion. The MWCNT has  2.19 eV and showed multiple peaks. A prominent peak at 329 nm with absorbance 0.6 which was blue shifted and a peak at 517 nm with absorbance 0.3 was red-shifted. The PSC with the MWCNT in the light had a fill factor of 0.53 but 0.47 was obtained for the PSC without the MWCNT.  The PSC with MWCNT had power conversion efficiency (PCE) of 40.1 % in the dark, a value which was 2.7 % higher than the PCE of 37.4 % obtained for the same cell in light. Furthermore, the PSC without the MWCNT in the dark had a fill factor of 0.87 while the PSC with MWCNT in the dark had a fill factor was 0.51. The PSC with MWCNT had better power conversion efficiency when in the dark than in light.