Upper limit to the theoretical efficiency of p-n homojunction and interfacial layer heterojunction solar cells

Thesis/Dissertation · Thu Jan 01 00:00:00 EST 1981

OSTI ID:6644796

Spitzer, M B

The physical mechanisms governing photovoltaic energy conversion in p-n homojunction and interfacial layer heterojunction (ILH) solar cells are examined. The usefulness of minority carrier mirrors (MCM) in such cells is studied by solving the minority carrier diffusion equation in the n- and p-type quasi-neutral regions of the cell, with boundary conditions representing MCM's at the ends of these regions. Nonzero values are also considered. It is shown that the MCM improves the open circuit voltage of the solar cell when it is located within a diffusion length of the junction between the n- and p-type regions. The effect of the MCM diminishes as the distance between it and the junction increases. The above analysis is applied to the direct gap materials CuInSe/sub 2/ (E=1.0eV) and GaAs (E=1.43eV). It is shown that the theoretical upper limit to the conversion efficiency for devices employing MCM's on the front and back is approximately 26% for a CuInSe/sub 2/ cell of width 2 microns. The analysis is also applied to cells made from silicon. A concept of internal light trapping is discussed; this trapping causes the light to undergo multiple reflections within the thin cell. By solving the minority carrier diffusion equation with appropriate generation function, it is shown that the upper limit to the efficiency is approximately 27%, for a cell of 15 microns in width. The ILH solar cell is examined. A model describng current transport in the ILH cell is discussed and applied to the MIS solar cell. A new type of solar cell, the back surface MIS cell, is considered. The model is applied to this type of cell and the efficiency is calculated. The model is applied to ITO-SiO/sub 2/-(p-type)Si SIS solar cell.

• OSTI ID: 6644796
• Resource Relation: Other Information: Thesis (Ph.D.)
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
HETEROJUNCTIONS
PHYSICAL PROPERTIES
HOMOJUNCTIONS
SILICON SOLAR CELLS
EFFICIENCY
COPPER SELENIDE SOLAR CELLS
GALLIUM ARSENIDE SOLAR CELLS
INDIUM SELENIDE SOLAR CELLS
MIRRORS
MIS SOLAR CELLS
N-TYPE CONDUCTORS
P-N JUNCTIONS
P-TYPE CONDUCTORS
THEORETICAL DATA
DATA
DIRECT ENERGY CONVERTERS
EQUIPMENT
INFORMATION
JUNCTIONS
MATERIALS
NUMERICAL DATA
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
SEMICONDUCTOR JUNCTIONS
SEMICONDUCTOR MATERIALS
SOLAR CELLS
SOLAR EQUIPMENT
140501* - Solar Energy Conversion- Photovoltaic Conversion