Doctoral dissertation on efficient technologies for storing and transporting solar energy 


Solar energy could be much more effective if it is be better stored and transferred. Storing and transferring solar power is possible by storing the energy directly into chemical bonds.
In his doctoral thesis M.Sc. Markku Hannula studies a form of artificial photosynthesis, where sun light in absorbed to synthetic light-activated materials and is stored as chemical energy of the molecules. Hydrogen has the highest energy density of all fuels and can be stored and converted into electricity on demand. Hannula has investigated the use of hydrogen molecules in the storage process. As the absorbing material in thin films, he has used titan dioxide. However, titan dioxide possesses challenges related to chemical stability of in ultra-thin films. In the thesis, Hannula has examined ways of making the thin films more stabile by thermal treatment. 
Hannula defended his doctoral thesis “Atomic Layer Deposited Titanium Dioxide Thin Films for Photoelectrochemical Water Splitting” on Monday, November 25, 2019. The responsible supervisor and Custos was Professor Mika Valden Tampere University and the Opponent Professor Joachim Schnadt from Lund University, Sweden. 


Read the doctoral thesis “Atomic Layer Deposited Titanium Dioxide Thin Films for photoelectrochemical Water Splitting”  
 

Doctoral thesis explores high-power VECSELs in new operating ranges


New flexible laser technologies offer applications in medicine, dermatology and biophotonics. In medical use lasers which have high penetration depth (750 nm light) into human tissues may be used.
M.Sc. Kostiantyn Nechay’s doctoral thesis “High-power VECSELs operating at the 700-800 nm wavelength range” contributes to the development of optically pumped vertical-external-cavity surface-emitting lasers (OP-VECSELs). This particular laser type couples features of solid-state lasers, such as a functional external resonator and optical pumping, with intrinsic gain versatility of semiconductor gain media. Such a successful combination made possible the creation of a remarkably flexible, multipurpose laser platform, capable of precise tailoring of output parameters in accordance even to the most strict applications, for instance in atomic, molecular, and optical physics. VECSELs deliver high-power and high-brightness emission at a vast wavelength range, but it has not been possible to utilize them in all spectral ranges. In his thesis, Nechay has developed a high-power direct-emitting VECSEL in the rare 700– 800 nm wavelength region. This thesis also contributes to finding viable ways of inexpensive large-scale manufacturing of VECSELs.

Kostiantyn Nechay defended his doctoral thesis on Friday 22, 2019.  The responsible supervisor and Custos Professor was Mircea Guina from Tampere University and the Opponent Professor Harri Lipsanen from Aalto University . 

Read the doctoral thesis “High-power VECSELs operating at the 700-800 nm wavelength range”