Dye-sensitised solar cells are a next-generation technology for generating electricity from sunlight that is flexible, adaptable to a variety of surfaces, affordable and environmentally friendly. This technology has the potential to revolutionise clothing, building materials and more.

Current energy challenges and alternatives

Currently, we rely on fossil fuels and nuclear power for most of our energy. Fossil fuels are a finite resource and their use causes environmental problems such as global warming. Nuclear power is highly efficient as an energy source, but it can cause catastrophic damage in the event of an accident, and there are significant problems with radioactive waste disposal. These issues have highlighted the need for sustainable energy sources. Among renewable energy sources, solar energy is attracting attention as a future energy source because it is inexhaustible, clean, and has a low environmental impact.

Dye-sensitised solar cells and the future of life

‘Ding, ding, ding, ding, ding!’ the alarm clock rang. I opened my heavy eyelids and looked at the clock: 8 o’clock. ‘I’m late for school!’ I thought to myself as I jumped up and started getting ready for school. After quickly getting ready, I checked my phone and saw that it had almost no battery left. Fortunately, I plugged my phone into my coat, which had a dye-sensitised solar cell attached to it, and it started charging. I was relieved to see that despite the cloudy weather, I could charge my phone in low light. When I arrived at school, my phone was already fully charged. A great start to the day.
This hypothetical scenario shows the future of dye-sensitised solar cells in real life. With these solar cells, we will be able to easily charge our electronic devices anywhere and use energy in an environmentally friendly way.

History and development of solar cells

The history of solar cells began in 1839, when French scientist Becquerel discovered that a metal electrode immersed in an electrolyte increased its current when exposed to light. The first solar cell was developed in the United States in 1954 and is known as the first generation solar cell. First-generation solar cells are made of crystalline silicon and currently account for about 80 per cent of the global solar cell market. However, this technology is expensive, has a limited range of light absorption, and is only about 18% efficient at generating electricity.
Second-generation solar cells are thin-film solar cells, which are divided into silicon and compound. This generation has a lower manufacturing cost than the first generation and can be made thinner, so it has a wide range of applications, but it still has the limitation of low power generation efficiency. The third generation of solar cells has improved on these shortcomings, with the advantages of a wider range of light absorption, higher power generation efficiency, and lower production costs. Dye-sensitised solar cells belong to this third generation of solar cells.

How dye-sensitised solar cells work

Dye-sensitised solar cells (DSSCs) mimic the natural process of photosynthesis to convert sunlight into electricity. Just as plants use chlorophyll to absorb light, these solar cells use nanoscale dye molecules to absorb light. The dye absorbs mainly visible light, which makes up about 40 per cent of sunlight, and releases electrons, which are transferred to an external circuit via electrodes to generate electricity. This process allows dye-sensitised solar cells to generate electricity in low light conditions, making them efficient indoors or on cloudy days.
The basic structure of a dye-sensitised solar cell is a ‘sandwich structure’. A thin glass substrate is coated with nanoparticles of titanium dioxide (TiO2) and a dye is bonded to it. The space between the electrodes is filled with an electrolyte that promotes oxidation/reduction reactions. When light absorbs the dye, electrons are released, which travel through the TiO2 to the electrodes, where they provide electrical energy via an external circuit.

Advantages of dye-sensitised solar cells

Dye-sensitised solar cells have a number of advantages. Firstly, they are flexible and can be applied to a variety of surfaces, including clothing and building windows. Unlike conventional silicon solar cells, they are translucent, so they can be used as building materials. They are also insensitive to changes in the angle of incidence of light, allowing them to operate stably in a variety of environments. They are highly efficient even in weak or scattered light, and can be produced in a variety of colours, making them highly aesthetically pleasing.
In addition, dye-sensitised solar cells are much cheaper to produce than conventional solar cells because they use low-cost, resource-rich materials, mainly TiO2. This makes them economically viable and, thanks to their environmentally friendly manufacturing process, they also emit less carbon dioxide. Thanks to these advantages, dye-sensitised solar cells have the potential to be used in a wide range of applications, including windows, cars, and clothing.

Challenges to overcome

However, dye-sensitised solar cells still have some challenges to overcome. The main one is that their power generation efficiency is lower than that of conventional silicon solar cells. Currently, dye-sensitised solar cells have an efficiency of 11-12%, compared to 18% for silicon solar cells. Another issue is the leakage of electrolyte. The electrolyte in dye-sensitised solar cells is liquid, which can evaporate or leak during long-term use. To solve this problem, solid-state electrolytes are being actively researched.
Recently, Professor Michael Grätzel’s team in Switzerland has developed a dye-sensitised solar cell using a solid polymer electrolyte to solve this problem. Further advances in this research will bring dye-sensitised solar cells closer to commercialisation.

Commercialisation and future prospects

Dye-sensitised solar cells are already under active research for commercialisation in many countries. Especially in Europe, Japan, and the United States, efforts are underway to commercialise them with national support, and in Korea, a project to use dye-sensitised solar windows as building materials is being promoted with the support of Daedeok Special Economic Zone. Once these technologies are commercialised, solar cells will be more widely used in our daily lives and we will be able to maximise the efficiency of energy use.
Recently, bags with dye-sensitised solar cells have been attracting attention. These bags can charge electronic devices indoors and outdoors using solar cells as thin as 1 mm or less. In the future, this technology will be applied to various fields such as clothing, electronics, and architecture, which will significantly change the way we live.
Dye-sensitised solar cells have great potential as a future energy source. Not only are they low-cost and environmentally friendly, but their flexibility and transparency make them promising for a variety of applications. With continued research and improvement, dye-sensitised solar cells will be commercialised, and we will be able to use solar energy freely, anytime and anywhere.