Quasi Fermi Levels in Semiconductor Photovoltaic Heterojunction

Heterojunctions Based on Amorphous Silicon: A Versatile Surface Engineering Strategy To Tune Peak Position of Redox Monolayers on Photoelectrodes

“…The rationality of combining these materials is justified in Scheme , which shows the energy levels associated with each semiconductor prior to the formation of the heterojunctions. When forming a heterojunction of two semiconductors, when the isolated semiconductors are brought in contact, electrons can move from the semiconductor with the higher Fermi level to the other, and an electric field is produced to balance this transfer . Under thermal equilibrium conditions, the effect tends to create a common equilibrium Fermi level for both semiconductors and generates an in-built junction potential that reflects the difference in work functions of each semiconductor .…”

“…With the effectiveness of modulating the light intensity to control the energetics of photoreactions on semiconductors, we propose a surface engineering strategy that allows one to modulate the peak position of redox monolayers without the need for changing illumination conditions. The concept is based on the use of heterojunctions, which are usually employed to generate large photovoltages and to influence the direction of flow of charge carriers on photovoltaic − and photocatalytic devices. , The hypothesis tested here is based on the principle that contact of materials in heterojunctions tends to lead to the creation of common equilibrium Fermi levels ( E F ) for both sides of the interface. , Such heterojunctions enable the manipulation of surface Fermi energy without the introduction of dopants. , From an electrochemical perspective, this principle indicates the possibility of tuning the potential required for electron transfer of redox monolayers according to the materials used to form the heterojunction.…”

Study of the Contributions of Donor and Acceptor Photoexcitations to Open Circuit Voltage in Bulk Heterojunction Organic Solar Cells

“…Orlowski et al [66] used the energetics of quasi-Fermi levels to study V OC in a heterojunction solar cell. They found that for a particular donor (p-type)-acceptor (n-type) heterojunction, the electron concentration (n) in the conduction band (LUMO) of the acceptor and the hole concentration (p) in the valence band (HOMO) of the donor, coupled with their respective quasi-Fermi levels, can create open circuit voltages like two independent cells.…”

Quasi Fermi Level Scan of Band Gap Energy in Photojunction

“…Continuously ongoing advanced studies aimed at indepth understanding of the physics of photovoltaic heterojunctions [1][2][3][4][5][6][7][8][9] and improvement of construction of solar cells [10][11][12][13][14][15] and ultraviolet sensitive photodetectors [16][17][18] are in line with the search of renewable energy sources supporting the sustainable civilization development. The comprehensive theory of solar cells exists and can be found in textbooks [3][4][5][6] convenient models describing particular aspects of electricity generation in a solar cell, facilitating experimental data interpretation or useful as an enlightening example are still welcome.…”

“…Illustration of quasi Fermi levels changes in a schematic structure of a photovoltaic heterojunction. F is the thermal equilibrium Fermi energy, F1p and F1n are relative changes of quasi Fermi levels of minority holes p and majority electrons n after generation of n = p carriers on side 1 of the junction (n-type, wide band gap Eg1), whereas F2n, F2p are the changes of quasi Fermi levels of minority electrons n and majority holes p on side 2 (p-type, medium band gap Eg2)[8].…”