Enhancing the Interface Contact of Stacking Perovskite Solar Cells with Hexamethylenediammonium Diiodide-Modified PEDOT:PSS as an Electrode.

Abstract

As an indispensable component of perovskite solar cells (PSCs), the commonly used Au and Ag electrodes still have some problems such as high cost and instability issues with regard to being corroded by iodide ions. In this paper, we report stacking perovskite solar cells (S-PSCs), which can avoid the use of precious metal electrodes and reduce the cost of devices and the requirements of equipment compared to conventional PSCs. The S-PSCs are composed of two semicells: a photoanode and a counter electrode (CE). For stacked devices, effective contact of the photoanode/CE interface is very important to the performance of the device. We used poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as the electrode and modified it by hexamethylenediammonium diiodide (HDADI2) to improve its physical and electrical properties. The surface of the HDADI2-modified PEDOT:PSS becomes rough and achieves higher adhesion, which enables the photoanode and CE to be sufficiently connected. In addition, the energy-level structure of the HDADI2-modified PEDOT:PSS matches better with that of the adjacent functional layers. Therefore, the S-PSCs performance has been significantly improved. Under an illumination area of 1 cm2, the power-conversion efficiency (PCE) of the S-PSCs can reach 15.21%. Moreover, the S-PSCs can be disassembled and assembled flexibly and repeatedly disassembled 500 times with almost no change in the PCE. This has a positive impact on cell maintenance and modular production.