Through this project a better understanding of low energy light absorbing organic dye designs has been found as a key intellectual merit. Multiple new concepts and structures were probed during this project. Dyes designed with specific architectural elements were found to have uniquely stabilized features after light absorption that enable the use of low energy light for processes such as charge separation across two different materials. The use of these dyes in solar cell devices has led to efficiencies of >10% solar-to-electric conversion using readily available, abundant materials. Theses dyes have shown world record dye-sensitized solar cell device photocurrent outputs with organic dyes at 25 mA/cm² which is dramatically higher than the prior reports of <20 mA/cm². This addresses a critical need within dye-sensitized light absorption fields since these technologies have been limited in only utilizing higher energy light in the visible region. With the invention of these dyes, substantially lower energy light than previously known is capable of being turned into electricity rather than being wasted. These dyes were also used in a record setting solar-to-fuel device that does not use any precious metals and is capable of directly making hydrogen from water and sunlight.

            Within the solar cell devices tested for this project, traditional designs have used a single dye anchoring point to the surface of the solar cell devices which are in a liquid environment. This single point anchoring systems has been widely suggested to be a weak point in terms of solar cell stability with this technology. If the dye detaches from the surface it would be ineffective in the liquid layer. Within this project a new dual anchor dye design approach has been but forward that shows exceptionally long-lasting dye-sensitized solar cell devices that pass a stress-test which is typically equated to 10 years of ambient environmental exposure with a less than 10% loss in performance over this time frame. This is an important finding for the furthering of the dye-sensitized solar cell field toward practical applications.

            Additionally, dyes in these systems work by moving electrons from one region of the molecule to another. A classic limitation to this approach is the region where the electrons begin at limits how easily the charge can be moved and often requires higher energy light to move charge than is desirable for many applications. Within in this project, a novel strategy was put forward that allows electrons to originate from multiple areas but transfer to the same region as if they had originated at a single area. This type of molecular funneling of electrons is preliminarily shown to be very encouraging and allowed surpassing of the limitations of systems with single regions of electron origin. This strategy was shown to work well in initial DSC devices and has led to dramatic performance enhancements over the classic benchmark systems.

            Concerning broader impacts, dye sensitized interfacial systems are at the interface of computational, physical spectroscopic, molecular synthetic, synthetic methods, surface, and materials chemistries. Additionally, optical physics and engineering widely explore dye-sensitized interfaces as well and will benefit from the knowledge gained under this project. Increased fundamental understanding of dye-sensitized solar cell device components in any one area impacts all remaining areas. One of the largest cross-discipline impacts from this project is in synthetic methods chemistry which is being directly expanded through studies on synthetic paths to previously inaccessible dye structures. Physical spectroscopic chemistry has also been directly affected by collaborative efforts to determine how long the dyes using the designs mentioned above exist in photoexcited states. Spectroscopic areas were also impacted in showing how these designs can allow for efficient, long-lived charge transfer across interfaces.

            Society in general benefits from a further developing of specialized skilled workers with good perspectives on future research directions in science and technology areas. Additionally, numerous students were employed and funded to continue their training and work during this project, which aids the US job market in maintaining lower unemployment rates. Boosting the education level of participants on this project also leads to general societal improvement by the introduction of members with enhanced problem-solving skill sets. Additionally, the fundamental research pursued on this award is influential toward a number of fields outside the primary (solar cell) field including: telecommunications, photoelectrochemical cells, secure displays, photosensors, night vision, and chemical methodology.

Last Modified: 09/09/2020
Modified by: Jared H Delcamp