Authors: Jasurbek Gulomov | Oussama Accouche | Rayimjon Aliev | Raymond Ghandour | Irodakhon Gulomova
Source: IEEE Access (article, 2023-01-01)
Field: Materials Science — Materials Chemistry

Investigation of n-ZnO/p-Si and n-TiO<sub>2</sub>/p-Si Heterojunction Solar Cells: TCAD + DFT This paper focuses on exploring new materials and structure as a means to increase the efficiency of solar cells. Since silicon is widespread on earth, it is desirable to study heterojunction solar cells made mainly of silicon and new materials. Therefore, ZnO/Si and TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /Si heterojunction solar cells were studied in this paper. First, the electrical and optical properties of ZnO and TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> were determined using the Perdew-Burke-Ernzerhof (PBE), PBE functional revised for solids (PBESol) and Perdew-Wang (PW91) functionals of the Generalized gradient approximation (GGA) in Density Functional Theory (DFT). The obtained results in various functionals are assessed and analyzed. It was found that geometric optimized structures of TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and ZnO is mechanical stable. Accordingly, in all functionals, the effective mass of the electron in ZnO and TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> proved to be smaller than that of the hole. The mobility of electrons and holes in ZnO was calculated to be 430.72 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> V <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> and 5.25 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> V <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> respectively. In TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , it was 355.27 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> V <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> and 46.38 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> V <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> . When PW91, PBESol, PBE functionals were used, the dielectric constant was determined to be 11, 11.5, 8.5 for ZnO and 9.5, 10, 9 for TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , respectively. According to the DFT results, it was determined that ZnO and TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> are transparent and mainly n-type direct semiconductors. According to device simulation, the maximum short-circuit current of ZnO/Si and TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /Si heterojunction solar cells is 18 mA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at a thickness of 80 nm and 15.3 mA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at a thickness of 40 nm. Finally, the average fill factor of ZnO/Si and TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /Si solar cells was 0.73 and 0.76 respectively. So TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> can be used as a transparent contact and ZnO as an emitter layer in a silicon-based solar cell. Heterojunction ; Density functional theory ; Silicon ; Materials science ; Physics ; Topology (electrical circuits) ; Optoelectronics ; Combinatorics ; Quantum mechanics ; Mathematics ZnO doping and properties ; Chalcogenide Semiconductor Thin Films ; Copper-based nanomaterials and applications