Quantum Mechanics Design of Two Photon Processes Based Solar Cells

Abstract

The photoelectric effect has been utilized in a wide range of optoelectronic sensors and solar energy conversion devices. To respond to today’s colossal energy demand there is a need for doing better than using this effect via the utilization of simple semiconductor homojunction based devices, since such structures cannot use all photons available for conversion into electricity. Actually, it is the inefficient response of the material to the various solar photons and the behaviour of photo-generated carriers that bar photovoltaic (PV) cells from fully harvesting the solar energy impinging on its surface. It is well known that there is no semiconductor that can be deployed for making a simple and low cost p-junction based solar cell that converts the entire solar spectrum. Hence, the development of efficient photovoltaic devices has been going through various technology pathways, one of which has led to a variety of multi-junction and cell stacks, i.e., tandem cells; each sub-cell is dedicated to converting a portion of the solar spectrum. Moreover, the conventionally chosen three sub-cell tandem scheme is being extended to stacks with larger number of subcells, regardless of the viability of the production technology. During the last five decades, several theoretical PV energy conversion efficiency thresholds have been established, each being for one type of PV device design. However, none has been reached in spite of the deployed tremendous efforts; the implementation turns out to be challenged by some specific constrains. High efficiencies attained thus far incorporated advances in material refinement, sophisticated cell design, state of the art fabrication technologies, and more importantly a relatively good understanding of the complicated and intertwined physics of charge carrier generation, recombination, and transport. However, for making new generation of high efficiency solar cells, new physics and technology paradigms have to be discovered. Current barriers to high conversion efficiencies are due to current understanding of the physics of photoelectric effect and related phenomena. Breaking those barriers, which would impact photovoltaic technologies, needs refinement of the physics of photoelectric effect with consideration of new materials and new device designs. For instance, development of “ideal” third generation solar cells requires understanding of the early stage of light-matter interaction mechanisms that occur at the nanoscale domains and the related quantum effects. Actually, the improved understanding of these phenomena is repositioning the used linear photoelectric effect occurring in homogenous and continuous planar shallow structure to one that occurs in a volumic