Plan Overview

Enough solar energy reaches the Earth each hour to meet the annual energy needs of every person on the planet. Yet despite this incredible abundance, the world’s countries have so far failed to make a serious investment in solar power generation. Though sunlight itself is free, the low efficiency and high cost of photovoltaic technology has prevented solar energy from competing economically with fossil fuels. This Plan examines how the complex chemistry behind photovoltaics has improved over the past 100 years, with a particular emphasis on the development of dye-sensitized solar cells (DSSCs).

In order to compete with fossil fuels, photovoltaics must become cheaper to produce while simultaneously increasing the efficiency with which they transform electromagnetic radiation from the Sun into electricity. DSSCs, which typically consist of a titanium oxide (TiO2) semiconductor coated with a ruthenium (Ru) dye, offer benefits in both these areas. In addition to being significantly cheaper to produce than traditional silicon (Si) based solar cells, they also offer better performance in sub-optimal light conditions (such as cloudy days).

Since the first cells were produced in 1991, chemists have steadily decreased their production costs and increased their efficiency of DSSCs. Although they still aren’t able to compete with fossil fuels in most markets, they remain one of the most promising solar technologies available today.

Excerpts

“At the moment, solar energy costs approximately $0.16/kWh. To be competitive with conventional energy sources the price needs to be between $0.06 and $0.10/kWh. As this paper will show, this goal is easily within reach provided serious steps towards developing solar energy are taken.”

“In a DSSC, photoexcitation of the dye results in an electron being injected into the semiconductor. This electron then moves to the electrode, creating a difference in electric potential.”

Plan Media

The structure of a dye-sensitized solar cell, along with an explanation of its absorption processThe molecular structures of two ruthenium-based dyes: Z910 (left) and K19 (right).