Three photovoltaic devices based on CH3NH3PbI3 (MAPbI3) perovskite using molybdenum oxide (MoO3), spiro-OMeTAD and poly(3-hexylthiophene-2,5-diyl) (P3HT) as hole transport materials (HTMs) with different highest occupied molecular orbital (HOMO) energy levels were simulated under AM 1.5G illumination of 1000 W m-2 intensity and light to electricity power conversion efficiency (PCE or g) of 16.12, 14.67 and 6.6% were obtained, respectively. The main aim of this study is to find an optimal HTM for perovskite solar cells (PSC). The device with MoO3 delivered the maximum fill factor of 76.49% and short-circuit current (JSC) of 21.38 mA cm-2, but suffered from the lower open-circuit voltage (VOC) compared to a device containing spiro-OMeTAD and P3HT. However, charge recombination and losses at interfaces between layers are two main factors that restrict cell performance. In this study, it is shown that MoO3 not only passivates the interfacial traps, but also enhances the charge extraction of the device. The enhancement in the performance of PSC by MoO3 passivation compared to two other devices is discussed in detail.
