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. •Five novel SAM molecules having various functional groups are presented to treat ITO surface.•SAM molecules have chemically attached to ITO surface and revealed permanent changes in the work function of ITO.•SAM molecules with different terminal groups have created different interactions with perovskite layer.•Terminal groups with electron donating moieties and halogen atom have indicated more prominent results.•Terminal groups with electron withdrawing moieties have indicated deterioration in device parameters.