High performance of NiO-Ag-NiO based semi-transparent perovskite solar cell

Abstract

In semi-transparent perovskite solar cells (ST-PvSC), the thicknesses and choice of charge transport layers and transparent electrode (TE) becomes more prominent in determining the performance and transparency of the device. In this work, we report the potential of NiO/Ag/NiO (NAN) as a top TE for ST-PvSC with methylammonium lead iodide (MAPI) as an absorbing material. Optical simulation based on the transfer matrix method (TMM) is used to optimize the NAN electrode and the whole device. NAN-TE with optimized NiO (37 nm)/Ag(9 nm)/NiO(34 nm) structure gives an average visible transmittance (AVT) of 86.60%. In addition, most of the prior works focus on using spiro-OMeTAD as hole transporting material (HTM), which has poor stability and is expensive. In our device architecture, NiO satisfying the energy level requirement is explored as an alternative to spiro-OMeTAD. Here in NAN-TE, the bottom NiO in contact with the perovskite layer not only works as a layer that helps to reduce the reflection loss due to the Ag layer but also as an HTM. In this work, we also studied the performance of different electron transporting materials (ETM) like TiO2, AZO, and ZnO in combination with the NAN-TE. When simulated with different ETM layers, TiO2 is found to be the best performing. The reported work enlightens the capability of NAN-TE for making devices not only semi-transparent but also in making a good interface with the active layer from the electrical point of view. Taking the optimized values of all layers in the device structure-Glass/ITO (100 nm)/TiO2 (40 nm)/MAPI (100 nm)/NiO (37 nm)/Ag (9 nm)/NiO (34 nm) a JSC value of 16.66 mA/cm2 and AVT of 31.49% for the device has been reported. Further, the use of NiO as HTM in place of spiro-OMeTAD has a greater impact on the stability and cost of the device.