One ofthe problems that calls for modeling in more than one dimension lies in the polycrystalline nature of CIGS and CdTe thin-film cells. The GBs in these materials have been observed by several scanning techniques. The boundaries between different grains disturb the periodicity of the crystal lattice and can create energy states within the band […]

This section will give some examples of problems that were addressed with 2D or 3D modeling and the knowledge that was gained through them. It does not by any means list all of them. 20.4.1 Equivalent-Circuit Modeling Examples In an equivalent-circuit model, like the one shown in Figure 20.2, a nonuniform device is represented with […]

To create a structure, one first defines the materials and contacts in the model. Then, the geometry and position for each layer and contact needs to be specified. After the structure is defined, the next step is defining the electronic properties such as doping profiles and band structure. The optical properties, such as the absorption […]

The output of the equivalent-circuit method is limited to calculating the current – density-voltage (J-V) characteristics of the device. To model cells more precisely, and to calculate physical properties such as band diagram, carrier density, photogenera­tion, recombination, and to simulate different characterization experiments, such as quantum efficiency, photoluminescence, admittance spectroscopy and others, one needs to […]

The equivalent-circuit approach is based on representing regions in a solar cell simply as diodes. A current source parallel with the diode represents light generation, and resistors can be connected to simulate parasitic resistances. A nonuniform device can then be represented as a network of nonuniform diodes. Figure 20.2 shows part of such a network, […]

The first step in creating a computational model is defining and providing dis­cretization of a 2D area or a 3D volume. Two main approaches to the discretization have been used for studying solar cells: equivalent-circuit modeling (Section 20.3.1) and solving semiconductor equations (Section 20.3.2). Equivalent-circuit modeling represents a solar cell device as a collection of […]

A standard 1D model simulates the electron and hole motion in the direction perpendicular to a planar junction. An enormous amount has been learned from this type of model. However, 1D models must also eliminate the inherent 3D nature of solar cells. Figure 20.1 shows a schematic of a typical thin-film solar cell. The carriers […]

Ana Kanevce and Wyatt K. Metzger 20.1 Introduction Research and development to expand solar cell use is based on finding ways to create more efficient devices, eliminate as many losses as possible, lower material usage, and use cheaper production processes. Empirical optimization is important but can be misguided and require significant time, effort, and cost. […]