Nanostructured surfaces and nanomaterials
Features of composite low-molecular-weight organic/inorganic silicon-based nanostructures for photovoltaic applications
Smertenko P.S.1, Roshchina N.M.1, Naumov V.V.1, 
Dusheyko M.G.2, Lukomsky D.V.2, Wisz G.3
1 Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine, Prospect Nauki, 41, Kyiv-03022, Ukraine. 
E-mail: petrosmertenko@gmail.com
2 National Technical University of Ukraine - Igor Sikorsky Kyiv Polytechnic Institute, Prospect Peremogy, 37, Kyiv 03056, Ukraine.
3 Uniwersytet Rzeszowski, Al. Rejtana, 16, Rzeszów 35-959, Poland.

Composite organic-inorganic hybrids are considered as a good alternative for light-weight thin-film photovoltaic (PV) cells [1]. Our approach is based on the next innovations: i) low-cost bio- or synthetic organic molecules suitable for broad band sunlight harvesting; ii) room-temperature process of self-organization and self assembly of 2D nanostructures; iii) simple technique of chemical deposition from aqueous solutions; iv) smart analysis of PV cells characteristics to optimize their functionality, combining the advantages of hybrid components. According to our study of various low-molecular-weight organic films fabricated with using hetero- cyclic amines grown on the patterned silicon substrates, such PV cells have the next features: 1) the efficiency of PV conversion is up to 9% (at AM1.5) depending on chemical composition and surface/interface morphology; 2) the best parameters are for the n-type Si-based hybrids of thiamine C12H12N4OS and clonidine C9H9Cl2N3 for layers of 100 nm thickness with net-like texture; 3) light absorption in such structures is accompanied by exitonic luminescence and re-emission in the visible and near-IR spectral range, which increases the overall PV efficiency. Despite the complicated mechanism of the carrier transfer in such hybrids, the classic models of electron-hole pair generation and charge separation are valid for describing their I-V curves, when the short circuit current (Isc) is a linear function of energy of irradiation, and the open circuit voltage (Voc) has a logarithmic dependence followed by saturation. Research has shown that even small changes in the design of PV cells can lead to essential differences in PV properties, but proper technological manipulations, for instance, in ohmic contacts, can help optimize PV parameters to the desired values that are acceptable for practical PV applications. 

1.	Smertenko P.S. et al. Formation of organic-inorganic hybrids by self- organization // E-MRS 2017 Fall Meeting, 18-21 Sep 2017, Warsaw.-P. D11.6.