Maximizing the optical performance of planar CH3NH3PbI3 hybrid perovskite heterojunction stacks

A vapour-phase reaction process has been used to deposit smooth and uniform CH3NH3PbI3 perovskite material to enable the measurement of its optical dispersion relations, n and k, by ellipsometry. Fitting was achieved with a combination of Tauc-Lorenz, critical point parabolic band (CPPB) and harmonic oscillators. We have used the dispersion relations in an all-optical model of new planar device architectures in order to establish design rules for future materials choices to maximize the short-circuit current (Jsc) performance. For 500nm of MAPI with no window layer, the maximum performance expected from the model is Jsc=21.63mAcm-2. The ability of thin layers (in the range 20-60nm) of a range of window layer materials (TiO2, WO3, ZnO, Nb2O5, CdS, and Cd0.4 Zn0.6S) to enhance the short-circuit current of the devices was investigated. The performance of the oxides showed interference behaviour, with the first maxima in their J sc curves exceeding the value achievable without a window layer. However, after the first maximum, the performance generally fell off with increasing thickness. The only material to stay greater than the no-window condition for the entire investigated range is WO3. The highest performance (J sc of 22.47mAcm-2) was obtained with 59nm of WO3, with that of TiO2, ZnO, and Nb2O5 being marginally lower. Parasitic absorption in CdS window layers caused the J sc to decrease for all non-zero thicknesses - it gives no interference enhancement and its use cannot be recommended on optical grounds. Use of the wider gap alloy Cd0.4Zn0.6S gave higher currents than did CdS but its performance was not so high as for the oxides. Observations are made on the practicalities of fabricating the target structures in the fabrication of practical PV devices

Accelerated optimization of transparent, amorphous zinc-tin-oxide thin films for optoelectronic applications

In the last decade, transparent amorphous oxide semiconductors (TAOS) have become an essential component of many electronics, from ultra high resolution displays to solar cells. However, these disordered oxides typically rely on expensive component metals like indium to provide sufficient charge carrier conduction, and their optoelectronic properties are not as predictable and well-described as those of traditional, crystalline semiconductors. Herein we report on our comprehensive study of the amorphous zinc-tin-oxide (a-ZTO) system for use as an indium-free, n-type TAOS. Using a combination of high-throughput co-deposition growth, high resolution spectral mapping, and atomistic calculations, we explain the development of disorder-related subgap states in SnO2-like a-ZTO and optical bandgap reduction in ZnO-like a-ZTO. In addition, we report on a composition-induced electronic and structural transition in ZnO-like a-ZTO resulting in an exceptionally high figure of merit, comparable to that of amorphous indium-gallium-zinc-oxide. Our results accelerate the development of a-ZTO and similar systems as indium-free TAOS materials

Well-Being, Activity, Mood and Optimistic Way of Thinking of Adolescent Athletes

Tyrimo tikslas – nustatyti sportuojančių paauglių savijautos, aktyvumo, nuotaikos ir optimistinio mąstymo būdo ypatumus. Tyrimo metu keliama hipotezė, kad sportinė veikla palankiai veikia paauglių savijautą bei optimistinį mąstymo būdą. Buvo tiriami dviejų amžiaus grupių 12,81±0,38 metų ir 16±0,49 metų po 90 sportuojančių paauglių. Tiriamųjų apklausai buvo pasitelktos dvi metodikos: viena – savijautai, aktyvumui ir nuotaikai įvertinti, o kita – optimistinio mąstymo būdui nustatyti. Matematinės statistikos hipotezėms tikrinti buvo taikomas Stjudento t kriterijus. Straipsnyje pateikiami duomenys atskleidžia, kad daugiau metų sportuojantys paaugliai statistiškai patikimai (p<0,05) skiriasi pagal visus tirtus parametrus. Nustatyta, kad ilgiau sportuojančių paauglių savijautos, aktyvumo, nuotaikos ir optimistinio mąstymo būdo rodikliai geresni nei pradedančių lankyti reguliarias sporto pratybas.Research aim was to establish peculiarities of wellbeing, activity, mood and optimism of adolescents engaged in sport. Research hypothesis was that sports activities would be beneficial to adolescents’ well-being and optimistic way of thinking. We investigated adolescent athletes of two age groups: 12.81±0.38 and 16±0.49 years of age, 90 athletes in each group. The survey included two measures: one for well being, activity and mood, the other – for the establishment of the optimistic way of thinking. Student’s t test was used to verify the hypotheses of mathematical statistics. The data in the research article show statistically significant differences (p<0.05) between adolescents engaged in sport and not engaged in sport in all investigated parameters. It was established that indices of well-being, activity, mood and optimistic way of thinking for athlete adolescents were higher compared to those of adolescents who had just started regular training sessions