Effect of functional groups of self assembled monolayer molecules on the performance of inverted perovskite solar cell

Organic-inorganic halide structure such as hybrid perovskite materials has been appeared as a pioneering approach to be used as a light harvester for cost-effective photovoltaic devices. Since light-absorber material is sandwiched between hole and electron transport layers, interfacial engineering starts playing significant role to develop high efficient perovskite solar cell (PSCs). Specifically, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) is used commonly as both electrode modifier material and hole transport layer in inverter type device architecture, but it also suffers from instability of PEDOT:PSS due to its ionic nature. Therefore, self-assembled monolayer (SAM) technic is regarded as a proper approach to overcome this problem. In this work, we present five novel SAM molecules with a feasible methodology to compare effect of electron donating and withdrawing terminal groups on the efficiency of inverted PSCs. Depending on the end group, SAM customization indicates a change in the work function of indium tin oxide (ITO) electrode, rectification of device parameters and passivation of the surface trap states. The present study fills a gap in the literature by indicating a comparative treatment route to more clearly understand interfacial issues between electrode-organic layers and perovskite structure for the fabrication of efficient inverted PSCs. This is the first study to undertake a longitudinal evaluation of the influence of both electron-donating and withdrawing terminal groups on the efficiency of inverted type PSCs.