Macroscopic versus microscopic photovoltaic response of heterojunctions based on mechanochemically prepared nanopowders of kesterite and n-type semiconductors
Journal Title: Semiconductor Physics, Quantum Electronics and Optoelectronics - Year 2017, Vol 20, Issue 4
Abstract
Mechanochemically prepared nanopowder of selenium-free kesterite Cu2ZnSnS4 (CZTS) in combination with n-type semiconductors, i.e., CdS, ZnO and TiO2, was tested in planar and bulk-heterojunction solar cells. The samples have been studied by macroscopic current-voltage (I-V) measurements and Kelvin-probe atomic-force microscopy (KPFM). KPFM images taken under light illumination showed the distribution of the potential across the surface, with negative potential on the n-type semiconductor domains and positive potential on the CZTS domains, which indicated charge separation at the interface of the counterparts. The best result was found for the CdS-CZTS composition, which showed a potential difference between the domains up to 250 mV. These results were compared with the planar heterojunctions of CdS/CZTS and TiO2/CZTS, where CZTS nanopowder was pressed/deposited directly onto the surface of films of the corresponding n-type semiconductors. Again, I-V characteristics showed that cells based on CdS/CZTS heterojunctions have the best performance, with a photovoltage up to 200 mV and photocurrent densities up to 0.1 mA/cm2. However, the carrier generation was found to occur mainly in the CdS semiconductor, while CZTS showed no photo-response and served as the hole-transporting layer only. It is concluded that sensitization of the kesterite powder obtained by mechanochemical method is necessary to improve the performance of the corresponding solar cells.
Authors and Affiliations
O. P. Dimitriev, D. O. Grynko, A. M. Fedoryak, T. P. Doroshenko, M. Kratzer, C. Teichert, Yu. V. Noskov, N. A. Ogurtsov, A. A. Pud, P. Balaz
Electronic structure of Ag8GeS6
For the first time, the energy band structure, total and partial densities of states of Ag8GeS6 crystal were calculated using the ab initio density functional method in LDA and LDA+U approximations. Argyrodite is direct-...
New evidence of the hopping nature of the excess tunnel current in heavily doped silicon p-n diodes at cryogenic temperatures
The new experimental data concerning the effect of magnetic field on electric properties of silicon diodes with high doping levels both in the emitter and base (conduction of which at low temperatures is determined by th...
Temperature effect on light polarization in uniaxial crystals
It has been shown that changes in temperature of uniaxial single crystal are accompanied by changes in the polarization plane angular position and the light intensity that subsequently passes through the polarizer, uniax...
Influence of intrinsic point defects and substitutional impurities (Cl, I-S) on the electronic structure of 2H-SnS2
It was performed the systematic investigation of chemical modification regularities of electronic structure at the composition changes of “ideal” 2H-SnS 2 crystal by using the self-consistent density functional theory me...
Nanograin boundaries and silicon carbide photoluminescence
The luminescence spectra of SiC crystals and films with grain boundaries (GB) on the atomic level were observed. The GB spectra are associated with luminescence centers localized in areas of specific structural abnormali...