Capacitance response of solar cells based on amorphous Titanium dioxide (A-TiO<sub>2</sub>) semiconducting heterojunctions

Hmoud. Al-Dmour; Hmoud. Al-Dmour

doi:10.3934/matersci.2021017

AIMS Materials Science

2021, Volume 8, Issue 2: 261-270. doi: 10.3934/matersci.2021017

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Capacitance response of solar cells based on amorphous Titanium dioxide (A-TiO₂) semiconducting heterojunctions

Hmoud. Al-Dmour ^,

Department of Physics, Faculty of Science, Mutah University, Mutah, 61710, Jordan

Received: 18 January 2021 Accepted: 30 March 2021 Published: 19 April 2021

In the present study, we studied the capacitance frequency response of amorphous titanium dioxide (A-TiO₂)/poly(3-hexylthiophene) (P3HT) solar cells. The capacitance was measured to provide information on interfacial layer between the two materials. At a low frequency, the capacitance increased because the frequency was lower than the relaxation time of the charge carriers, thus providing evidence of the formation of a depletion region at the P3HT/A-TiO₂ interface. The loss tangent was measured for applied voltage ranging from 0 to 1.5 V and the frequencies from 20 Hz and 1 MHz. Peaks in the loss tangent appeared as a function of the applied voltage due to changes in the transport and accumulation mechanisms of charge at the interface and the presence of oxygen molecules in the TiO₂. The resulting C-V curves were used to calculate dopant concentration and the barrier's potential, which was found to 10¹⁷ cm⁻³ and 0.6 V, respectively. This confirmed the presence of a depletion region placed in the P3HT region and the validated barrier's potential effect on the open circuit voltage value. It was also shown that the light J-V characteristics of the A-TiO₂/P3HT solar cells were independent of the ambient conditions because the conductivity of P3HT and the depletion region were not affected.
- interfacial layer,
- loss tangent,
- amorphous TiO₂,
- barrier potential,
- relaxation time
Citation: Hmoud. Al-Dmour. Capacitance response of solar cells based on amorphous Titanium dioxide (A-TiO2) semiconducting heterojunctions[J]. AIMS Materials Science, 2021, 8(2): 261-270. doi: 10.3934/matersci.2021017

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Abstract

In the present study, we studied the capacitance frequency response of amorphous titanium dioxide (A-TiO₂)/poly(3-hexylthiophene) (P3HT) solar cells. The capacitance was measured to provide information on interfacial layer between the two materials. At a low frequency, the capacitance increased because the frequency was lower than the relaxation time of the charge carriers, thus providing evidence of the formation of a depletion region at the P3HT/A-TiO₂ interface. The loss tangent was measured for applied voltage ranging from 0 to 1.5 V and the frequencies from 20 Hz and 1 MHz. Peaks in the loss tangent appeared as a function of the applied voltage due to changes in the transport and accumulation mechanisms of charge at the interface and the presence of oxygen molecules in the TiO₂. The resulting C-V curves were used to calculate dopant concentration and the barrier's potential, which was found to 10¹⁷ cm⁻³ and 0.6 V, respectively. This confirmed the presence of a depletion region placed in the P3HT region and the validated barrier's potential effect on the open circuit voltage value. It was also shown that the light J-V characteristics of the A-TiO₂/P3HT solar cells were independent of the ambient conditions because the conductivity of P3HT and the depletion region were not affected.

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