We report on order–disorder related band gap changes in Cu2ZnSn(S,Se)4 solar cells which are induced by post-annealing. The band gap changes of the absorber are detected utilizing electroreflectance and analyzed by comparison with predictions of the stochastic Vineyard model. This yields a critical temperature of TC=195 °C above which the Cu2ZnSn(S,Se)4 absorber layer is entirely disordered within the Cu–Zn layers of the kesterite unit cell. The temporal evolution of the band gap during annealing shows that the equilibrium value is reached on a timescale in the order of hours, depending on the annealing temperature. In contrast to other experimental techniques, electroreflectance precisely measures the band gap and is not influenced by defect-mediated radiative recombination.

No need for a solid template: Hollow gold spheres (see TEM image) have been realized through a microemulsion approach. The spheres have a wall thickness of 2–6 nm and an inner diameter of 20–40 nm.

Dedicated to Professor Dieter Fenske on the occasion of his 60th birthdayThe stabilization of binary aggregates of main group elements [E 0x E y ] qÀ in the coordination sphere of transitionmetal ions M nþ (E' or E ¼ Group 13±15 or 16 element), and thus the formation of structures that contain ternary heavy atom frameworks, is an area of increasing research activity. [1±16] Besides diverse range of molecular and crystal structures, the synthesis of some ternary M/E'/E systems that show polymeric anion substructures representing ™open solidstate structures∫, as found in Rb 3 [AgGe 4 Se 10 ]¥2 H 2 O [10] or K 2 [MnSnS 4 ], [11] have recently attracted attention. Such compounds combine both zeolite-type and semiconducting properties. If binary alloys or salts of binary anions are used for the construction of the E'/E aggregates instead of separate components, the investigations additionally serve to study the reaction behavior and stability of these systems in the presence of transition-metal compounds. However, most reports on the latter deal with binary reactants of Groups 15/16, [1, 13±16] for example the synthesis of [PPh 4 ] 2 -[Mn(CO) 3 (As 3 Se 3 ) 5 ] by using [As 4 Se 4 ]. [13b] Only most recently, were some results published that considered the surfactanttemplated solvothermal synthesis of mesoporous solids like (C 16 H 33 NC 5 H 5 ) x [Pt y Sn 0 4 Se 10 ] (x ¼ 1.9±2.8; y ¼ 0.9±1.6).[12] One of our current aims is to generate coordination compounds by reacting binary anions of Groups 14 and 16.

This thesis would not have been possible without the support of many people, and I am eternally grateful for all the support. I hope to see some of you again in the future! The main objective of my PhD project was to study defects in semiconducting oxides within the research project FOXHOUND headed by Prof. Lasse Vines, my main supervisor. I am grateful to Lasse for the opportunity to work on this topic. I have learned much more than I imagined I would when I started. Lasse, you have been a patient and competent supervisor who always took time to answer endless streams of questions. Prof. Truls Norby and Assoc. Prof. Anette Eleonora Gunnaes were co-advisors for my PhD project. I am grateful to Truls for introducing me to the chemist's view on defects and his group FASE/ELCHEM. I am truly sad that I did not get to collaborate more with Anette. I also want to thank Prof. Eduard Monakhov and the late Prof. Bengt Gunnar Svensson. Both were valuable unofficial advisers on my PhD, and helped moving my work along. Most of my work was carried out within the semiconductor physics group at the University of Oslo (LENS), and I would like to thank of all its current and former members for contributing to my work in many ways. There are some people who deserve special thanks. First of all, I am grateful to my long-term office mates Torunn, Sigbjørn and Josef for sharing many conversations and being there for each other. Secondly, I am particularly grateful to all my close collaborators at LENS, and especially Julie, Philip, Ymir, Vegard R., Vegard O., Viktor and Espen. I also want to thank our engineers (Micke, Halvor, Christoph and Viktor) and administrative staff (Marit, Heine and Kristin) for keeping things running! Also, thanks to Ilia, Robert, Vegard R. and Jon for taking care of the needs of the E-Lab and the Online-Setup. I was a co-supervisor for two master students: Vegard R. and Espen. I hope both of them learned something from me, because I did definitely learn from them. I am particularly grateful to Vegard R. for being a large part in building the steady-state photo-capacitance setup used in this work. I also would like to thank all my co-authors from outside of Oslo: Frank from Dresden, Willem, Walter and Danie from Pretoria, Klaus and Zbigniew from Berlin, Antti from Aalto and Joel from California. Special thanks to Willem, Walter and Danie for hosting me in Pretoria and showing me around. Last but not least, I would like to thank my family and my friends for their support!

The hexachalcogenodistannates K 6 [Sn III 2 Se 6 ] or Li 4 [Sn IV 2 Te 6 ]·8en were recently reported to simultaneously act as mild oxidants and chalcogenide sources in reactions with CoCl 2 / LiCp* (Cp* ϭ pentamethylcyclopentadienide) while the SnϪE (E ϭ Se, Te) fragment is not kept in the products, e.g. [(Cp*Co) 3 (µ 3 -Se) 2 ], [(Cp*Co) 3 (µ 3 -Se) 2 ][Cl 2 Co(µ 2 -Cl) 2 Li(thf) 2 ] or [(Cp*Co) 4 (µ 3 -Te) 4 ]. In search of related reagents with possibly different reaction behavior, we isolated and crystallographically characterized isotypic compounds [enH] 4 [Sn IV 2 Se 6 ]·en (1), and [enH] 4 [Sn IV 2 Te 6 ]·en (2) (en ϭ 1,2-diaminoethane), that result from an uncommon disproportion/re-arrangement reaction: distannate(III) K 6 [Sn 2 E 6 ] (E ϭ Se, Te) was reacted with en·2HCl to yield 1 or 2 under disproportion of Sn III to Sn II and Sn IV . Another pathway was necessary to synthesize the respective but solvent-free thiostannate [enH] 4 -