Photovoltaic Materials

Photo of a researcher using a large-scale laser scanner (LSLS) that uses a laser to scan PV modules and produces an output that can be used to analyze the modules.

A researcher analyzes the output current of a PV module. With the LSLS system, Rick Matson focuses the laser beam as it scans a commercial polycrystalline silicon PV module. He uses the laser scanner to identify causes of uneven performance in a module. On the computer screen a line scan and LIBIC map of the scanned area show nonuniformities in current output.

Three general technical areas — crystalline silicon, thin films,and modules — are discussed, with further levels of detail provided within the discussions.

Crystalline silicon technology is advancing through research on materials, devices, and processes. With improved starting material, we can produce better solar devices. With improved devices, we can increase efficiencies and decrease fabrication costs. And with improved processes, we also reduce costs.

Thin Films of special photovoltaic materials produce solar cells with relatively high conversion efficiencies, but use much less material than crystalline silicon cells. We will discuss the following key materials or technologies: amorphous silicon (a-Si), copper indium diselenide (CIS) and its alloys, cadmium telluride (CdTe), and thin films using a multijunction design.

PV modules are optimized to improve performance beyond present limits. To optimize the modules, we must know and control technical details such as doping profiles, morphology, short-range order, stoichiometry, and process uniformity. Research also helps to decrease the costs of module manufacturing.