deletions | additions       diff --git a/CdTe_photovoltaics_PV_is_the__.tex b/CdTe_photovoltaics_PV_is_the__.tex  index 8e6856b..a534fa6 100644  --- a/CdTe_photovoltaics_PV_is_the__.tex  +++ b/CdTe_photovoltaics_PV_is_the__.tex 
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CdTe photovoltaics (PV) is the only thin film technology with lower costs ($\frac{\$}{W}$) than conventional solar cells made of crystalline silicon in multi-kilowatt systems. In August of 2014, First Solar® was able to accomplish a CdTe solar cell efficiency of 21.5\% \cite{firstsolar2015} while their commercial high volume PV modules have 17.0\% \cite{Sinha_2013}.   The theoretical upper bound of efficiency, the Shockley-Queisser (SQ) limit \cite{Shockley_1961} for a PV with a band gap of 1.49 eV (CdTe) under the standard AM1.5G flat-plate solar spectrum \cite{nreal} is 32.2\%. This is relevant when comparing with other similar thin film PVs such as GaAs, which have a relative efficiency of $ \zeta_{SQ}=\frac{ \zeta_{real} }{ SQ_{limit} }= \frac{28.8}{33.1} \approx 0.87 $ \cite{Vossier_2015} \cite{Yablonovitch_2012}. Under this metric, CdTe research grade PVs have a value of $\zeta_{SQ}=0.667$. and commercial PV modules have $\zeta_{SQ}=\frac{17.0}{32.2}\approx 0.52$. There is much room for improvement to make this technology more affordable. improvement.  This paper discusses the optical and electrical factors that reduce the efficiency of a single junction CdTe PV below the SQ limit and provides recommendations on closing this 9.0-15.2\% gap.