This blog post examines the principles and characteristics of dye-sensitized solar cells and explores how transparent and flexible solar technology will transform our future across diverse fields like architecture and electronics.
In the winter of 2013, the SNS drama ‘Infinite Power’ aired on Korean internet video sites. Set in a boarding house, the drama depicted the struggles and wanderings of a young generation facing harsh realities—job seekers, exam candidates, and others. What stood out most was the ‘infinite power device,’ which also gave the drama its title. The ‘Infinite Power Device’ is, literally, a device capable of providing endless power. The long-held dream of the boarding house owner, a character in the drama, was to create this ‘Infinite Power Device’. The owner collected scrap metal and researched day and night for his dream, but others saw him and mocked him, saying he was chasing an impossible, absurd dream. Thus, ‘perpetual motion’ was seen as nothing more than an unrealistic, impossible dream for humanity. But what about a phone that never runs out of power, no matter how much you use it? If, in fact, using the phone could charge it using the light emitted from its display, this would represent a significant step closer to humanity’s long-held dream of perpetual motion. Non-silicon solar cells, specifically dye-sensitized solar cells (DSSC), can make this once purely imaginary lifestyle a reality.
Dye-sensitized solar cells (DSSCs) look quite different from the solar cells most people imagine. Solar cells that generate electricity from sunlight or heat can be categorized as silicon-based or non-silicon-based. The solar cells commonly known from calculators or solar streetlights are silicon-based solar cells. Dye-sensitized solar cells belong to the non-silicon category. Unlike conventional solar cells, non-silicon solar cells use inorganic or organic materials as their base, not polysilicon. Composed of organic dye and a glass substrate, dye-sensitized solar cells take on a novel form, resembling transparent glass.
How can this simple piece of glass become a cell? The principle of dye-sensitized solar cells draws inspiration from the photosynthesis process in plants, making the two processes highly similar. First, on an n-type nanoparticle semiconductor oxide electrode where dye molecules are chemically adsorbed onto the surface, sunlight generates electron-hole pairs (excited electrons). This resembles the process in photosynthesis where electrons become excited by sunlight absorbed by chlorophyll. The formed electron-hole pairs are injected into the conduction band of the semiconductor oxide and transferred through the nanoparticle interface to the transparent conductive film, generating a current. This is analogous to the process in photosynthesis where electrons pass through the electron transport chain to generate energy. Finally, the operation of the dye-sensitized solar cell is completed when the hole generated in the dye molecule receives an electron from the redox electrolyte and is reduced again. This process can be likened to the filling of holes in photosynthesis by stealing electrons through the oxidation of water.
Dye-sensitized solar cells utilizing this principle can achieve transparent color characteristics because they employ nano-sized oxides capable of transmitting part of the visible light spectrum and dyes that can exhibit different colors. Therefore, while conventional solar cells were opaque and thus used on rooftops, dye-sensitized solar cells, due to their transparent color properties, can be used in windows or personal portable devices. Moreover, their transparency offers a significant advantage: the ability to harvest light from both sides. Unlike conventional solar cells, this dual-sided light harvesting allows for vertical installation and orientation in either the east-west direction. Consequently, power generation is possible before sunrise and after sunset, and even when installed facing east or south, equivalent or higher power output can be achieved.
Dye-sensitized solar cells also offer advantages in energy conversion efficiency. According to existing research, when comparing silicon-based solar cells with dye-sensitized solar cells, the latter demonstrated higher energy conversion efficiency. This is because the decrease in conversion efficiency due to temperature increase was smaller in terms of energy conversion efficiency variation with cell temperature. Furthermore, their light sensitivity also showed a smaller decrease in conversion efficiency due to sensitivity reduction compared to conventional cells. Similarly, the variation in conversion efficiency with incident angle highlighted the efficiency advantage of dye-sensitized cells.
Since the expiration of the original dye-sensitized solar cell (DSSC) patent in April 2008, active efforts to commercialize them have been pursued worldwide. However, while silicon-based solar cells still dominate the market, non-silicon solar cells are achieving gradual progress in specific application areas. Currently (2025), non-silicon solar cells, including DSSCs, are being applied in Building-Integrated Photovoltaics (BIPV), Internet of Things (IoT) devices, and wearable electronics, with products leveraging flexibility and design freedom emerging.
Experts had anticipated that the commercialization of non-silicon solar cells would accelerate around the mid-2020s, but large-scale market entry has been slower than expected due to production cost and efficiency issues. However, perovskite solar cells (PSCs) are gaining attention for their high power conversion efficiency and low manufacturing costs, increasing their potential to replace conventional silicon solar cells. Recent research indicates that perovskite-silicon tandem solar cells have achieved higher efficiency (over 30%) than silicon-only cells, entering the commercialization phase.
An era where human imagination becomes reality is approaching—think phones that never need charging or windows that generate energy. While technical challenges remain, continuous R&D and investment suggest non-silicon solar cells will expand their market share in the photovoltaic sector.
