Proceedings of nanoGe International Conference on Perovskite Solar Cells, Photonics and Optoelectronics (NIPHO19)
DOI: https://doi.org/10.29363/nanoge.nipho.2019.057
Publication date: 21st November 2018
Recently perovskite based solar cells have emerged as a photovoltaic (PV) technology with Advantages such as low-cost materials, tunable band gap and high efficiency.
The perovskite main drawback is the lack of long-term stability. The common organic-inorganic hybrid perovskite used in solar cells is three dimensional (3D) structural framework
corresponding to the general chemical formula AMX3 (A=organic cation, M= metal cation, X= halide anion). By adding a longer organic cation (R) that does not fit into the octahedral perovskite array, the dimensionality of the perovskite changes resulting in layered quasi-tow dimensional (quasi-2D) perovskite structure, corresponding to the general chemical formula R2An-1MnX3n+1 In this structure the additional longer organic cation acts as a barrier that separates the 3D perovskite octahedra. The number of 3D perovskite layers (n) is determined by the ratio between the long organic group (R) and the small organic cation (M).
The improvement of stability in the quasi-2D structure comes at a cost of the cell’s efficiency; the barrier hinders the charge transport in the perovskite layer. As we decrees the ‘n’ value we can get higher stability[1] but the cost in efficiency increases as well.
an addition of NH4SCN as an additive in the quasi-2D perovskite has shown to improve the efficiency, the improvement is attributed to a change in the quasi-2D orientation, the addition of NH4SCN is said to achieve a vertically orientated qusi-2D perovskite which leads to improved PV performance[2].
In this work we attempt to achieve a better understanding of the role of NH4SCN in the perovskite structure, and the mechanism which leads to improved PV performance of the qusi-2D structure.