Solar Energy Materials and Solar Cells, Vol.195, 323-329, 2019
Highly stable semi-transparent MAPbI(3) perovskite solar cells with operational output for 4000 h
We present high stability of semi-transparent methyl ammonium (MA) lead triiodide perovskite (MAPbI(3)) solar cells with sputter-deposited polycrystalline NiOx hole transport layer (HTL) and indium tin oxide (ITO) back contact. We have demonstrated high thermal stability of the MAPbI(3) perovskite devices with the NiOx HTL and glass encapsulations, showing no performance degradation at 85 degrees C over 1000 h in dark. They showed instability, however, under 1 sun illumination at similar to 30 degrees C. Here, we demonstrate that the combination of the NiOx HTL and the ITO for both top and bottom electrodes of the perovskite solar cells can solve this instability problem. This approach resulted in highly stable semitransparent devices with the average visible light transmittance (AVT) above 11% and the power conversion efficiency (PCE) of 12.5%, showing steady power output nearly 4000 h of continuous operation at MPPT under 1 sun illumination. While the use of poly[bis(4-phenyl)(2,4,6-trimethylphenyl) (PTAA) HTL resulted in the semitransparent devices with higher PCE of 13.6%, their device stabilities were much inferior to the NiOx HTL based devices. These results indicated that a rather classical MA based perovskite, MAPbI(3), is indeed a stable photovoltaic material with the proper choice of the interface layers and electrode materials, and the use of the sputter-deposited NiOx HTL together with the ITO back contact is one of the key elements to overcome the stability problem in the lead halide perovskite solar cells.