Enhancing the efficiency of the intermediate band solar cells by introducing: carrier losses, alloying and strain

Joey Wang, Wanshu Xiong, Judy Rorison

Research output: Contribution to journalArticle (Academic Journal)peer-review

2 Citations (Scopus)
284 Downloads (Pure)

Abstract

A detailed balance model is used with a blackbody radiation function to
determine the efficiency of an intermediate band solar cell including carrier losses from the intermediate band. The effect of the energy gap of the host semiconductor is examined as a function of the intermediate band position in the energy gap and the host semiconductor energy gap. Generally the optimum intermediate band level is found to decrease within the energy gap to mitigate the carrier losses and it is found that carrier losses are less detrimental to small energy gap materials. We therefore focus the study on the role of carrier losses in wide bandgap semiconductor intermediate band solar cell systems such as the GaN semiconductor with an Mn impurity band. Experimentally the Mn acceptor level in the GaN energy gap is found to be 1.8 eV above the valence band which is 199 meV off the ideal IB neglecting losses which reduces the efficiency to 21.36%. We demonstrate how carrier losses can be introduced into the system to shift the optimum IB position. Introducing carrier losses of 70% from the intermediate band, shifts the optimum intermediate band position to 1.8 eV above the valence band and increases the efficiency to 23.41%. We compare this to the effect of alloying the GaN and introducing biaxial strain to shift the effective position of the Mn impurity band within the bandgap to increase the
efficiency.
Original languageEnglish
Pages (from-to)38-43
Number of pages6
JournalIET Optoelectronics
DOIs
Publication statusPublished - 16 Mar 2017

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