Synergetic effect of TiO2/ZnO bilayer photoanodes realizing exceptionally high VOC for dye-sensitized solar cells under outdoor and indoor illumination

Harnessing energy from the surrounding light using indoor photovoltaics has gained momentum to address the carbon footprint resulting from used and dead batteries. Dye-sensitized solar cells (DSCs) have emerged as one of the most efficient and sustainable indoor light harvesting alternatives which can significantly reduce the environmental impact of batteries. Energy harvesting and managing circuits in these devices demand higher open circuit potentials (V-OC). Nevertheless, recombination losses frequently lower the open-circuit potential in DSCs, especially when illuminated indoors. We present an innovative TiO2/ZnO bilayer architecture capable of delivering higher V-OC by carefully controlling the conduction band (CB) position and recombination losses. By sensitizing this innovative bilayer electrode with MS5 dye and a [Cu(dmp)(2)](1+/2+) redox mediator, we achieved a record V-OC of 1.27 V from a single junction device under Air Mass 1.5 Global (AM 1.5G), 100 mW cm(-2) solar irradiation and 1.295 V under higher intensity LED light (200 mW cm(-2)). These bilayer devices also demonstrated impressive V-OC of 1.025 V under 1000 lux compact fluorescent light (CFL) and light emitting diode (LED) illumination and could autonomously power a temperature sensor using a single device of 0.24 cm(2) active area. This work highlights the potential of modifying the semiconductor and device architecture to achieve higher V-OC in DSCs, which is essential for integrating these photovoltaic devices with smart IoT devices making them autonomous and sustainable.

Automated summary

Harnessing energy from indoor light using dye-sensitized solar cells (DSCs) has gained momentum as an efficient and sustainable alternative to reduce the environmental impact of batteries. Researchers have developed an innovative TiO2/ZnO bilayer architecture that can deliver higher open-circuit potential (V-OC) by controlling the conduction band position and recombination losses. These bilayer devices achieved record V-OCs under different light sources and could autonomously power a temperature sensor. This work highlights the potential of modifying semiconductor and device architecture to make photovoltaic devices autonomous and sustainable.