Sn-doped CdS: A New Intermediate Band Material for Solar Cells

In this paper, the electronic structure and optical properties of CdS doped by Sn with different concentrations were investigated by first principles. The calculation results of electronic structure show that the doping of Sn can produce a deep impurity level band in the band structure of CdS. The calculation results of optical property show that Sn doping can increase the light absorption coefficient and conductivity of CdS. The overall calculation results show that Sn doping can produce stable intermediate band structure and significantly improve the optical property of CdS.

Key parameters of textured silicon solar cells of 26.6% photoconversion efficiency

A new approach to modeling the parameters of high efficiency textured silicon solar cells (SCs) has been presented. Unlike conventional optimization formalisms, our approach additionally includes such important factors as the non-radiative Auger recombination of excitons via deep impurity levels as well as electron-hole pairs recombination in the space charge region. A simple phenomenological expression offered by us earlier for the external quantum efficiency of the textured silicon solar cells with account of the photocurrent in the long-wave part of the absorption spectrum has been also used. Applying this approach, the key parameters of textured silicon SCs, namely: short-circuit current, open-circuit voltage and photoconversion efficiency, have been theoretically determined. The proposed formalism allows calculating the thickness dependence of photoconversion efficiency, which is in good agreement with the experimental results obtained for the heterojunction SCs with the record photoconversion efficiency of 26.6%. The offered approach and the results of applying this phenomenological expression for the external quantum efficiency of the photocurrent in the long-wave part of the absorption spectrum can be used to optimize the characteristics of high efficiency textured SCs based on monocrystalline silicon.

Strong Coupling of Electron and Nuclear Spins: Outlook and Prospects

In this chapter, some prospects in the field of electron and nuclear spin dynamics are outlined. Particular emphasis is put ona situation where the hyperfine interaction is so strong that it leads to a qualitative rearrangement of the energy spectrum resulting in the coherent excitation transfer between the electron and nucleus. The strong coupling between the spin of the charge carrier and of the nucleus is realized, for example in the case of deep impurity centers in semiconductors or in isotopically purified systems. We also discuss the effect of the nuclear spin polaron, that is ordered state, formation at low enough temperatures of nuclear spins, where the orientation of the carrier spin results in alignment of the spins of nucleus interacting with the electron or hole.

Electron Spin Relaxation Beyond the Hyperfine Interaction

Here, some prospects for future studies in the field of electron and nuclear spin dynamics are outlined. In contrast to previous chapters where the electron interaction with multitude of nuclei was discussed, in Chapter 8 particular emphasis is put on a situation where hyperfine interaction is so strong that it leads to a qualitative rear rangement of the energy spectrum resulting in coherent excitation transfer between electron and nucleus. The strong coupling between the spin of the charge carrier and of the nucleus is realized; e.g., in the case of deep impurity centers in semiconductors or in isotopically purified systems. We also discuss the effect of the nuclear spin polaron; that is, the ordered state, where the carrier spin orientation results in alignment of spins of the nucleus interacting with the electron or hole. Such problems have been briefly discussed in the literature but, in our opinion, call for in-depth investigation.

Synergistic effects of nonmetal co-doping with sulfur in anatase TiO2: a DFT + U study

S + NM co-doping could induce a stronger local electric field and eliminate the deep impurity energy bands of S mono-doped TiO2.