Dye-sensitized solar cells attain a new power conversion performance record

• Mesoscopic dye-sensitized solar cells (DSCs) were designed in 1990s by Brian O'Regan and Michael Grätzel, taking on the latter's name-- the world-famous Grätzel cells. DSCs convert light into electrical power via photosensitizers-- dye compounds that absorb light and inject electrons into an array of oxide nanocrystals which ultimately are collected as electrical current.

In DSCs, photosensitizers are connected (" adsorbed") to the surface of nanocrystalline mesoporous titanium dioxide films that are drunk with redox active electrolytes or a solid charge-transport material-- the entire design aims to generate electric power by moving electrons from the photosensitizer towards an electrical output like a device or a storage unit.

DSCs are clear, can be produced in multiple colors for low cost, as well as are currently being used in skylights, greenhouses, as well as glass facades, such as those decorating the SwissTech Convention Facility. In addition, lightweight flexible variations of DSCs are currently commercially sold on a big range for electrical powering of portable electronic devices such as earphones as well as e-readers, too in the Internet of Things by using ambient light.

Current innovations in photosensitizers and various other components of DSCs have actually boosted the performance of DSCs under both solar sunshine and ambient light problems. However the trick to enhance DSC efficiency, depends on understanding as well as controlling the assembly of dye molecules externally of titanium dioxide nanoparticle films that prefer the generation of electrical charge.

One method is cosensitization, a chemical fabrication technique that generates DSCs with two or more various dyes that have complementary optical absorption. Cosensitization has actually moved the power-conversion performances of DSCs in the direction of world-record values since it can conceivably combine dyes that can absorb light from across the entire light spectrum. Nonetheless, cosensitization has actually also proved ineffective in many cases given that locating the appropriate pairs of dyes that can accomplish high light absorption and power conversion performance needs painstaking molecular design, synthesis, and also testing.

Now, scientists from the teams of Grätzel as well as Anders Hagfeldt at EPFL have actually developed a means of improving the packing of two freshly created photosensitizer dye molecules to boost the DSC's solar efficiency. With each other, the new photosensitizers can collect light quantitatively throughout the entire visible domain. The new technique entails pre-adsorbing a monolayer of a by-product of hydroxamic acid on the surface of nanocrystalline mesoporous titanium dioxide. This reduces the adsorption of the two sensitizers, allowing the development of a well purchased as well as densely packed layer of sensitizer at the titanium dioxide surface.

With this approach, the team had the ability to develop DSCs with a power conversion performance of 15.2% for the very first time under typical international simulated sunlight, with long-lasting operational stability examined over 500 hours. By raising the energetic location to 2.8 cm2, the power conversion efficiency covered 28.4%-- 30.2% over a vast array of ambient light strengths in addition to exceptional stability.

The study appears in Nature.

The writers write, "Our findings lead the way for facile access to high performance DSCs as well as offer promising prospects for applications as power supply and battery replacement for low-power digital devices that utilize ambient light as their power resource."