Multi-layering of a nanopatterned TiO2 layer for highly efficient solid-state solar cells

A facile process to prepare multi-layered nanopatterned photoanodes (MNPs) is presented with well-arrayed mesoporous inorganic oxide layers. The MNPs were prepared with multiple stacking of nanopatterned TiO2 layers using a sacrificial polystyrene (PS)-thin film layer, which not only guided the stacking TiO2 layer but also was removed completely by calcination without generating cracks. The prepared MNPs exhibited large enhancement of the light harvesting property by increasing the number of nanopatterned TiO2 layers, through multiple reflection of the incident light from the periodic embedded channels formed between the nanopatterned layers. The photovoltaic efficiency was optimized with a 3-layered nanopatterned photoanode exhibiting a 73% Jsc and a 65% power conversion efficiency enhancement compared with a cell with a flat TiO2 layer for I2-free solid-state dye-sensitized solar cells. Korean researchers have developed a multilayered, nanopatterned photoanode that traps significantly more light than conventional devices. Dye-sensitized solar cells based on titanium dioxide (TiO2) are an emerging low-cost photovoltaic technology, but efficiency gains must be made before they can be used in practical applications. Eunkyoung Kim and colleagues from Yonsei University in Seoul investigated ways to enhance light reflectivity in dye-sensitized solar cells by using a polydimethylsiloxane stamp to form nanoscale channels into a TiO2 paste. After removing the nanostamp and performing annealing, they coated the patterned TiO2 with a sacrificial polystyrene film that preserved the periodic channels when the stamping process was repeated. The team produced a three-layered TiO2 nanoarchitecture that captured light transmissions normally lost as waste, resulting in a 65% gain in photoconversion efficiency over flat TiO2 layers. A facile process to prepare multi-layered nanopatterned photoanodes (MNPs) is presented with well-arrayed mesoporous inorganic oxide layers. The MNPs were prepared by multiple stacking of nanopatterned TiO2 layers using a sacrificial polystyrene-thin film layer, which not only guided the stacking TiO2 layer but also was removed completely by calcination without generating cracks. The MNPs were applied to solid-state solar cells, to exhibit an enhancement of 73% and a 65% in Jsc and power conversion efficiency (PCE), respectively.