Environmental Engineering Reference
In-Depth Information
Chapter 6
Effective Harvesting of Photons
6.1 Introduction
The market penetration of photovoltaic (PV) solar technology is
hindered by its high cost, and various new methods have been
introduced to overcome this barrier. High e
ciency multi-layer
tandem solar cells, new low-cost materials and device structures,
and the mass production of PV modules are some of them. In
the case of tandem solar cells, the present trend is to move from
one-junction devices to double-junction, triple-junction, and multi-
junction structures in order to enhance the absorption of photons
from the solar spectrum. The current method is to use tunnel
junctions to combine several cells made out of materials with
different bandgaps. This chapter presents disadvantages of the
current practice of using a tunnel junction approach and introduces
an alternative method of effective harvesting of photons to achieve
higher conversione
ciencies.
6.2 Tandem Solar Cells
Themainaimofthetandemsolarcellistoabsorbamajorpartofthe
solar spectrum and, hence, increase the e
ciency of the device by
