Effect of Polyethylene Glycol Incorporation in Electron Transport Layer on Photovoltaic Properties of Perovskite Solar Cells

Due to the characteristics of high electron mobility, ambient stability, proper energy level, and low processing temperature, zinc oxide (ZnO) has become a very promising electron transport material for photovoltaics. However, perovskite solar cells fabricated with ZnO reveal low efficiency because perovskite crystals may decompose thermally on the surface of ZnO as a result of proton transfer reactions. In this study, we are the first to incorporate an inexpensive, non-toxic polyethylene glycol (PEG) into ZnO and explore the passivation effect on the electron transport layer of perovskite solar cells. Suspension stability, surface roughness, electrical conductivity, crystal size, and photovoltaic properties with respect to the PEG incorporation are analyzed. The experimental results revealed that PEG incorporation effectively passivated the surface defects of ZnO, increased the electrical conductivity, and suppressed the charge recombination. The photocurrent density could increase from 15.2 to 19.2 mA/cm2, an increase of 27%.