Heavily phosphorus-doped silicon nanoparticles as intermediate layer in solar cell based on IFO/p-Si heterojunction

The goal of this work is to investigate the effect of heavily phosphorus-doped silicon nanoparticles (NP-n(+))Si introduced between the p-type silicon substrate and indium fluorine oxide (IFO) thin film on the performance of the IFO/(NP-n(+)ipp(+))Cz-Si (Czochralski silicon)/indium tin oxide (ITO) heterojunction solar cell. Nanoparticles were deposited on p-Si surface from ethanol-based colloidal suspension by ultrasonic spray coating. The IFO and ITO films were grown by ultrasonic spray pyrolysis. A reference solar cell without nanoparticles with IFO/(pp(+))Cz-Si/ITO structure was also fabricated and studied. SEM, EDX, XPS, and FTIR spectroscopy, reflection and external quantum efficiency spectra, Suns-V-oc measurements were used for the analysis. It was shown that the phosphorus doping level of (NP-n(+)) Si is of about 3 x 10(20) cm(-3). After deposition, NPs are covered with SiOx layer which is removed by HF dip. The mean NPs size is of about 5.7 nm. An increase in duration of NPs deposition from 7 to 19 min leads to an increase in density of NPs from 5.6 x 10(11) to 1.06 x 10(12) cm(-2) and, consequently, to an increase in NPs surface coverage from 10.6% to 27.5%. IFO/(NP-n(+)/pp(+))Cz-Si solar cell with NPs surface coverage of 27.5% have shown noticeably higher power conversion efficiency of 13.2% in comparison with 11.9% efficiency obtained for the reference cell. This result is achieved due to increased open-circuit voltage (571 mV in the NPs-based solar cell against 484 mV for the reference cell). (C) 2015 Elsevier Ltd. All rights reserved.