The synthesis of new generation inorganic nanoparticles and their application as hole transport layer in perovskite solar cells

Perovskite solar cells (PSCs), which have an important role in photovoltaic technology in recent years, have exceeded one of the most important obstacles in the way of commercialization with efficiency values above 23%. However, the high cost of organic-based spiro-OMeTAD, which is used as a hole transport layer (HTL) in high efficiency cells, and its adverse effects on long-term cell stability due to the hygroscopic additives inside, are main factors that limit the commercialization potential of this cell type. In this study, the integration of inorganic CuCrO2 (CCO) and CuFeO2 (CFO) materials into the n-i-p configuration PSCs were successfully carried out. These inorganic materials can be obtained with a much cheaper price as compared to spiro-OMeTAD as well as do not have any negative effect on the stability of the device due to lack of additives. As compared to spiro-OMeTAD, HTL materials produced by hydrothermal method offer good hole mobility and have suitable energy levels with both perovskite and metal top electrode. As a result of the optimization studies, conversion efficiencies were obtained as 16.7% (16.04 ± 0.40) for CCO and 15.5% (15.12 ± 0.28) for CFO with negligible hysteresis. These slightly lower values, as compared to the spiro-OMeTAD-based cell with 19.4% (18.87 ± 0.34) efficiency, were attributed to possible recombination events and current leakages occurring at the interfaces. However, it has been found that inorganic HTL based cells exhibit a successful posture from both humidity dependent shelf-life (60 days) and operational stability (500 hours) measurements. Estimated cost analysis is also reported and it can be said that inorganic HTL materials with high efficiency/cost ratio and long term stability are good alternative for the transformation of commercialization potential of PSCs into practice.