ABSTRACT
This chapter presents the advantages and disadvantages of the new practice of using a tunnel junction approach and introduces an alternative method of effective harvesting of photons to achieve higher conversion efficiencies. The market penetration of photovoltaic (PV) solar technology is hindered by its high cost, and various new methods have been introduced to overcome the barrier. The main aim of the tandem solar cell is to absorb a major part of the solar spectrum and increase the efficiency of the device by increasing the short circuit new density. The conduction band of one device is connected to the conduction band of the adjacent device; the connection is parallel. In series connections, charge carriers are slowed down at each tunnel junction, increasing recombination and reducing the current collection in the external circuit. Photo-generated charge carriers at any depth of the device are effectively separated, accelerated, and collected in the external circuit.
