A critical analysis of luminescent solar concentrator terminology and efficiency results

Recent efforts to synchronise laboratory protocols for measuring luminescent solar concentrator (LSC) efficiencies, and to use consistent terminology, has been driven by a prior lack of consensus on both terminology and the reporting of experimental results. This analysis seeks to understand how terminology in the field of luminescent solar concentrators has been used in the past, and to recommend the most clear and consistent terminology that should be used for future publications. LSCs for electrical power generation, referred to as luminescent solar concentrator photovoltaics (LSC-PV), should be treated as integrated photovoltaic cells. Consequently, the power conversion efficiency (PCE) and external quantum efficiency (EQELSC(λ)) should be reported, as they would be with any other photovoltaic device. The term “optical efficiency” has been defined inconsistently throughout the literature, with several different efficiency expressions, and thus it should be interpreted with great care. The highest values for the three most common LSC efficiency metrics have been examined in detail and their validity and significance have been assessed. Among the examined results, it has been assessed that the highest reliable results are a PCE of 7.1%, an optical power efficiency (ηopt) of 7.8% and an external photon efficiency (ηext) of 6.8%. A significant number of highest efficiencies reported have used questionable calculation methods meaning those efficiency values should not be used as a comparison for current and future publications. Additionally, reporting optical power efficiency is not recommended unless optical power is relevant to the device application.<p></p>