Novel Low Cost Hole Transporting Materials for Efficient Organic-inorganic Perovskite Solar Cells

Organic-inorganic halide perovskite solar cells have recently emerged as high performance photovoltaic devices with low cost, promising for affordable large-scale energy production. The power conversion efficiency (PCE) from solar energy to electricity in solid state photovoltaic devices has risen from 10 % to over 20 % within two years of development. To date, a relatively expensive organic hole-conducting molecule with low conductivity, namely Spiro-OMeTAD (2,2',7,7'-tetrakis(N,N-di-p-methoxyphenyl-amine) 9,9'- Spirobifluorene), is employed widely to achieve highly efficient perovskite solar cells. Here, we report two low cost candidates to replace spiro-OMeTAD for perovskite solar cells, Poly(3,4-ethylenedioxythiophene) (PEDOT) and copper thiocyanate (CuSCN). Stabilized power conversion efficiency of 6.6 % and 9.1 % can be obtained when the new materials are used as the hole-conductor respectively, comparing to 9.6 % for device using Spiro-OMeTAD.