Photovoltaic Behaviors in an Isotype n-TiO ₂ /n-Si Heterojunction

Abstract

An n-TiO2/n-Si isotype heterojunction is fabricated by depositing TiO2 thin films onto n-Si substrates. Obvious photovoltaic behaviors are observed in this isotype heterojunction. The open circuit voltage and short circuit current of the heterojunction can reach 123 mV and 20 µA/cm 2 , respectively. The mechanism for the photovoltaic behaviors can be understood in terms of the band alignment of the heterojunction. The results reported may provide a feasible route to easily available and low-cost isotyped photovoltaic devices.

High-performance self-powered photodetector based on organic/inorganic hybrid van der Waals heterojunction of rubrene/silicon*

“…[40,56,57] The E C in the band diagram with energy of 4.05 eV represents the bottom energy level of the conduction band of silicon wafer, while the E V with energy of 5.17 eV represents its top edge of valence band. [58] Furthermore, the E F is defined as their corresponding Fermi energy levels. When the p-type rubrene crystal films are deposited onto the n-type Si substrates, their majority carriers will diffuse with each other due to the difference of energy levels, therefore, a large built-in electrical field and potential barrier can be formed at their interface under thermal equilibrium condition.…”

Tailored Interfaces of the Bulk Silicon Nanowire/TiO2 Heterojunction Promoting Enhanced Photovoltaic Performances

“…24,25 However, early efforts to fabricate n-Si/n-TiO 2 isotype heterojunction solar cells have yielded very low efficiencies, to the tune of 0.0005% with a small fill factor (FF) of 21%. 24 Subsequently, researchers fabricated a TiO 2 heterojunction in conjunction with silicon NWs, which seemingly improved both short-circuit current density and open-circuit voltage, essential traits for the fabrication of solar cells. 25 Meanwhile, p-type silicon coated with anatase TiO 2 is limited by unfavorable band-bending at the heterojunction.…”

“…Indeed, n-type silicon NWs can also be used in conjunction with anatase TiO 2 to form an n + –n isotype heterojunction with favorable band-alignment to produce good solar cell devices. , However, early efforts to fabricate n-Si/n-TiO 2 isotype heterojunction solar cells have yielded very low efficiencies, to the tune of 0.0005% with a small fill factor (FF) of 21% . Subsequently, researchers fabricated a TiO 2 heterojunction in conjunction with silicon NWs, which seemingly improved both short-circuit current density and open-circuit voltage, essential traits for the fabrication of solar cells .…”

“…Thus, the open-circuit voltage ( V oc ) from the cell will be the V oc of the TiO 2 /front contact junction minus V oc of the SiNWs/TiO 2 junction as shown in Figure a. However, photogenerated holes in the Si move toward TiO 2 to recombine with electrons because of a built-in electric field in the space-charge region for n-SiNWs/n-TiO 2 . , Hence, the open-circuit voltage ( V oc ) for n-SiNWs/n-TiO 2 will be the sum of the V oc at the n-TiO 2 /front contact junction plus the V oc at n-SiNWs/n-TiO 2 junction because, the Fermi energy ( E F ) and band energies of n-SiNWs and n-TiO 2 shift upward at open circuit conditions under illumination as shown in Figure a.…”