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.