Dipartimento di Scienza dei Materiali, Università degli Studi di Milano Bicocca , via R. Cozzi 55, 20125 Milano, Italy.
Optical Materials Engineering Laboratory, ETH Zurich , Leonhardstrasse 21, 8092 Zurich, Switzerland.
ACS Appl Mater Interfaces. 2017 Nov 22;9(46):40180-40186. doi: 10.1021/acsami.7b10829. Epub 2017 Nov 7.
Upconversion is a photon-management process especially suited to water-splitting cells that exploit wide-bandgap photocatalysts. Currently, such catalysts cannot utilize 95% of the available solar photons. We demonstrate here that the energy-conversion yield for a standard photocatalytic water-splitting device can be enhanced under solar irradiance by using a low-power upconversion system that recovers part of the unutilized incident sub-bandgap photons. The upconverter is based on a sensitized triplet-triplet annihilation mechanism (sTTA-UC) obtained in a dye-doped elastomer and boosted by a fluorescent nanocrystal/polymer composite that allows for broadband light harvesting. The complementary and tailored optical properties of these materials enable efficient upconversion at subsolar irradiance, allowing the realization of the first prototype water-splitting cell assisted by solid-state upconversion. In our proof-of concept device the increase of the performance is 3.5%, which grows to 6.3% if concentrated sunlight (10 sun) is used. Our experiments show how the sTTA-UC materials can be successfully implemented in technologically relevant devices while matching the strict requirements of clean-energy production.
上转换是一种光子管理过程，特别适合利用宽带隙光催化剂的水分解电池。目前，此类催化剂无法利用 95%的可用太阳光子。我们在这里证明，通过使用低功率上转换系统，可以增强标准光催化水分解装置在太阳辐照下的能量转换效率，该系统回收部分未利用的亚带隙入射光子。上转换器基于敏化三重态-三重态湮灭机制（sTTA-UC），在染料掺杂弹性体中获得，并通过允许宽带光捕获的荧光纳米晶体/聚合物复合材料增强。这些材料的互补和定制光学特性可在亚太阳光辐照下实现高效上转换，从而实现首个由固态上转换辅助的水分解电池原型。在我们的概念验证设备中，性能提高了 3.5%，如果使用集中阳光（10 太阳），则提高到 6.3%。我们的实验表明，sTTA-UC 材料如何在满足清洁能源生产严格要求的同时成功应用于技术相关设备。
