Fabrication of Bifacial-Modified Perovskites for Efficient Semitransparent Solar Cells with High Average Visible Transmittance

Semitransparent perovskite solar cells (PSCs) that possess a high-power conversion efficiency (PCE) and high average visible light transmittance (AVT) can be employed in applications such as photovoltaic windows. In this study, a bifacial modification comprising a buried layer of [4-(3,6-Dimethyl-9H-carbazol-9-yl) butyl] phosphonic acid (Me-4PACz) and a surface passivator of 2-(2-Thienyl) ethylamine hydroiodide (2-TEAI) was proposed to enhance device performance. When the concentrations of Me-4PACz and 2-TEAI were 0.3 mg/mL and 3 mg/mL, opaque PSCs with a 1.57 eV perovskite absorber achieved a PCE of 22.62% (with a VOC of 1.18 V) and retained 88% of their original value after being stored in air for 1000 h. By substituting a metal electrode with an indium zinc oxide electrode, the resulting semitransparent PSCs showed a PCE of over 20% and an AVT of 9.45%. It was, therefore, suggested that the synergistic effect of Me-4PACz and 2-TEAI improved the crystal quality of perovskites and the carrier transport in devices. When employing an absorber with a wider bandgap (1.67 eV), the corresponding PSC obtained a higher AVT of 20.71% and maintained a PCE of 18.73%; these values show that a superior overall performance is observed compared to that in similar studies. This work is conductive to the future application of semitransparent PSCs.