Perovskite Solar Cells using Carbon Nanotubes both as Cathode and Anode

Organic-inorganic halide perovskite solar cells (PSCs) have received much attention on account of their high power conversion efficiency while providing the advantages of solution processability and potentially low fabrication cost. However, at the current level of halide perovskite solar cell technology, these advantages cannot be maximized due to structural and material limitations. Here, we provide a solution to these problems by all-carbon nanotube (CNT) electrode-based PSCs that employ fully solution-processed layers. This study has two central aims: to demonstrate the use of CNT films as both the anode and cathode and to devise an entirely solution-processed configuration with a rational cost analysis. We show that [6,6]-phenyl C61-butyric acid methyl ester (PC61BM)-soaked CNTs can function as the cathode, and also that poly(3-hexylthiophene-2,5-diyl) (P3HT)-soaked CNTs can function as the anode, playing a role in energy alignment. Our flexible fully solution-processed all-CNT-electrode PSCs, with a configuration of CNT-P3HT/poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) /CH3NH3PbI3 (MAPbI3)/CNT-PC61BM, gave a PCE of 7.32% with good mechanical flexibility. This work realizes innovations in the materials, costs, and processing of inverted-type PSCs.