Solar energy storage and conversion is a key technology for the future realization of a sustainable energy production worldwide. The utilization of low-energy photons by means of upconversion (UC) processes has the main advantage of the upconversion process and solar energy-harvesting devices being considered and optimized independently, without affecting the particular physical characteristics of the operating sunlight excited material or device architectures. The UC-device must function efficiently with noncoherent light excitation, under light intensities comparable with those obtainable from moderate concentrated sunlight (1 to 20 suns, AM1.5); such a low degree of concentration allows usage of Fresnel-type focusing systems. We report chemical synthesis and efficient functioning of a triplet–triplet annihilation upconversion-based device, harvesting the entire deep-red spectral range of the sun irradiation (Δλ∼142 nm) in a gap-free manner.
The specific application of photon upconversion (UC) in photovoltaics is only possible when the following
requirements are fulfilled: First, the excitation intensity necessary for effective UC needs to be small (as low as
1Wcm-2) − comparable with light intensities obtainable from the moderate concentrated sunlight. Second, the excitation spectral power density required for effective UC needs to be comparable with those of the terrestrial
sun irradiation (in order of 100μWnm-1). Third, efficient UC must be obtained by non-coherent light excitation
(sunlight). And last but not least – compatibility between the UC device and the photovoltaic device, including
good optical coupling has to be realized.
Up to now the triplet-triplet annihilation-supported upconversion (TTA – UC) is the only upconversion
process excited with moderate concentrated sunlight. Our group demonstrates UCd based on various UCmolecular
systems efficiently transforming the NIR and IR-A part of the sun spectrum into the VIS-range,
operating at moderate sunlight concentrations (10-50 suns, AM1.5). The next important accomplished
requirement is the transfer of the hydrophobic UC-molecular system from an organic solvent to the aqueous
environment. These new aqueous UC systems with high efficiencies ensure good sealing of the UC device and in
this way its compatibility with different solar cells.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.