Enhanced efficiency of inverted bulk heterojunction solar cells with embedded silica nanoparticles

Abstract

Incorporation of nanoparticles in the active layer is one of the possible approaches to improve the efficiency of bulk heterojunction organic solar cells (BHJ OSCs). Here, we have synthesized silica nanoparticles (SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> NPs) using the modified stober method and studied the dispersion of various concentrations of SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> NPs in poly (3-hexylthiophene), [6, 6]-phenyl C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">61</sub> -butyric acid methyl ester (P3HT: PCBM) blend. It was found that the inverted geometry device with concentration of 2 wt% of SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> NPs and having the structure ITO/ZnO (NPs)/P3HT: PCBM: SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> NPs/MoO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> /Al shows a maximum efficiency of 1.95 %, which is more than 32 % larger compared to devices without SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> NPs. UV-Vis absorption measurements suggest that the incorporation of SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> NPs into a P3HT: PCBM blend improves the absorption. This absorption enhancement, supported also by finite difference time domain (FDTD) calculations of Mie scattering, results in the observed efficiency improvement.