Quantum modeling of two-level photovoltaic systems

Some Applications of Quantum Mechanics, 2012

Renewable and Sustainable Energy Reviews, 2015

In this review, we present and discussed the main trends in photovoltaics (PV) with emphasize on the conversion efficiency limits. The theoretical limits of various photovoltaics device concepts are presented and analyzed using a flexible detailed balance model where more discussion emphasize is toward the losses. Also, few lessons from nature and other fields to improve the conversion efficiency in photovoltaics are presented and discussed. From photosynthesis, the perfect exciton transport in photosynthetic complexes can be utilized for PV. Also, we present some lessons learned from other fields like recombination suppression by quantum coherence. For example, the coupling in photosynthetic reaction centers is used to suppress recombination in photocells.

Phys. Chem. Chem. Phys., 2015

The high quantum efficiency of photosynthetic complexes has inspired researchers to explore new routes to utilize this process for photovoltaic devices. Quantum coherence has been demonstrated to play a crucial role within this process. Herein, we propose a three-dipole system as a model of a new photocell type which exploits the coherence among its three dipoles. We have proved that the efficiency of such a photocell is greatly enhanced by quantum coherence. We have also predicted that the photocurrents can be enhanced by about 49.5% in such a coherent coupled dipole system compared with the uncoupled dipoles. These results suggest a promising novel design aspect of photosynthesis-mimicking photovoltaic devices.

2009

We present a theoretical model for the behavior of the propagation of electrons in a photovoltaic cell with some Bohm quantum potential corrections. The system describes the dynamic of the electron density and the current density functions. A numerical solution for the 1-dimensional case based on the method of the backward finite differences is given. Also, some analytical solutions for 3-dimensional case are proposed.

Entropy, 2021

We present a novel theoretical approach to the problem of light energy conversion in thermostated semiconductor junctions. Using the classical model of a two-level atom, we deduced formulas for the spectral response and the quantum efficiency in terms of the input photons’ non-zero chemical potential. We also calculated the spectral entropy production and the global efficiency parameter in the thermodynamic limit. The heat transferred to the thermostat results in a dissipative loss that appreciably controls the spectral quantities’ behavior and, therefore, the cell’s performance. The application of the obtained formulas to data extracted from photovoltaic cells enabled us to accurately interpolate experimental data for the spectral response and the quantum efficiency of cells based on Si-, GaAs, and CdTe, among others.

The Journal of Physical Chemistry C, 2017

The dynamics of photoinduced charge generation is studied for donor-acceptor (D-A) organic interfaces, with focus on the interplay of quantum dynamics, decoherence effects and recombination. A coarse-grained molecular envelope function model is developed to enable the investigation of large scale D-A heterojunctions, taking into account morphology and molecular orientation as well as the underlying quantum nature of the system. Simulations show that upon photoexcitation Frenkel excitons delocalize over several molecules in < 300 fs. At the interface, they dissociate without dwelling in intermediate charge transfer states, evincing that exciton motion and dissociation cannot be describe by point particle models. Moreover, as decoherence suppresses the excitonic quantum coherence length, it also decreases the geminate recombination rate. Although ultrafast coherent charge separation is more efficient at early times and, particularly, for excitons created at the interface, diffusion becomes important for excitons created far away from the D-A interface. In this case, decoherence provides a slower but steadier diffusion migration that protects the exciton from geminate recombination. We discuss the balance between charge dissociation and transport in OPV devices and photosynthesis.

Physical Review B, 2008

We present a microscopic theory of bipolar quantum well structures in the photovoltaic regime, based on the nonequilibrium Green’s function formalism for a multiband tight-binding Hamiltonian. The quantum kinetic equations for the single particle Green’s functions of electrons and holes are self-consistently coupled to Poisson’s equation, including intercarrier scattering on the Hartree level. Relaxation and broadening mechanisms are considered by the inclusion of acoustic and optical electron-phonon interaction in a self-consistent Born approximation of the scattering self-energies. Photogeneration of carriers is described on the same level in terms of a self-energy derived from the standard dipole approximation of the electron-photon interaction. Results from a simple two-band model are shown for the local density of states, spectral response, current spectrum, and current-voltage characteristics for generic single quantum well systems.

2009

Absorption and emission in inorganic bipolar solar cells based on low dimensional structures exhibiting the effects of quantum confinement is investigated in the framework of a comprehensive microscopic theory of the optical and electronic degrees of freedom of the photovoltaic system. In a quantum-statistical treatment based on non-equilibrium Green’s functions, the optical transition rates are related to the conservation of electronic currents, providing a quantum version of the balance equations describing the operation of a photovoltaic device. The generalized Planck law used for the determination of emission from an excited semiconductor in quasi-equilibrium is replaced by an expression of extended validity, where no assumptions on the distribution of electrons and photons are made. The theory is illustrated by the numerical simulation of single quantum well diodes at the radiative limit.

Structural dynamics (Melville, N.Y.), 2017

Electron transfer and subsequent charge separation across donor-acceptor heterojunctions remain the most important areas of study in the field of third-generation photovoltaics. In this context, it is particularly important to unravel the dynamics of individual ultrafast processes (such as photoinduced electron transfer, carrier trapping and association, and energy transfer and relaxation), which prevail in materials and at their interfaces. In the frame of the National Center of Competence in Research &quot;Molecular Ultrafast Science and Technology,&quot; a research instrument of the Swiss National Science Foundation, several groups active in the field of ultrafast science in Switzerland have applied a number of complementary experimental techniques and computational simulation tools to scrutinize these critical photophysical phenomena. Structural, electronic, and transport properties of the materials and the detailed mechanisms of photoinduced charge separation in dye-sensitized ...