Ambient-air fabrication with inorganic/polymer hole transport layer: Towards low cost perovskite solar cells

Abstract

Despite achieving remarkable efficiency in last decade in perovskite solar cells (PSCs), major drawback remains poor stability of these cells in ambient conditions. In addition, highest efficiencies have been reported in PSCs employing high cost hole transport layer (HTL), 2,2,7,7-tetrakis(N,N-di-p-methoxyphenylamine)-9,9- spirobifluorene (Spiro-OMeTAD), fabricated under stringent conditions in N2 filled glove boxes. In the present paper, we combine low cost and air-stable HTLs such as CuSCN and MEH-PPV, to fabricate the PSCs under ambient air (∼RH 80%). The HTLs were characterized thoroughly using UV-Vis spectroscopy, electrochemical technique and atomic force microscopy before employing in the fabrication of the PSCs. The devices characterized under ambient conditions showed slightly higher short-circuit current density (JSC∼4.88 mA/cm2) and open-circuit potential (VOC∼0.70V) for PSCs based on MEH- PPV as HTL as compared to those prepared with CuSCN (JSC ∼4.04 mA/cm2, VOC∼0.65V) as HTL. The impedance spectroscopy results show that the difference in performance of PSCs occurs due to charge-carrier imbalance at the MEH-PPV/perovskite interface.