Color-temperature dependence of indoor organic photovoltaic performance

Abstract

Organic materials are uniquely suited for indoor light energy harvesting because they absorb mostly in the visible spectrum and the absence of ultraviolet light minimizes their degradation. However, the performance of photovoltaic devices under indoor lighting depends on the correlated color temperatures (CCTs) of the light sources but has not been examined previously. Here we study organic photovoltaics with different combinations of donor and acceptor materials under white light-emitting diode (LED) illumination. The current density – voltage (J - V) measurements were performed under illuminance of 1000 lx at nominal LED CCTs of 3000 K, 4000 K, and 6000 K. Absorption spectra of neat and blended films and device external quantum efficiency were measured. Our results show that active layer absorption in the blue LED emission region determines the short-circuit current density (J sc ) increase from 3000 K to 6000 K CCT; the more the active layer absorbs at 450 nm, the larger the J sc increase under higher CCTs. We find that the normalized fractional absorption of the active layer at 450 nm needs to be > 0.85 to eliminate a decrease in power conversion efficiency as the CCT is varied from 3000 K to 6000 K. This work highlights the unique tunability of organic absorbers that is difficult to achieve in inorganic materials and provides guidance on how to select organic absorbers for specific applications under different indoor illumination conditions. • Study color-temperature dependence of organic photovoltaic performance under white light-emitting diode illumination. • Active layer absorption at 450 nm determines the power conversion efficiency (PCE) under cool white light. • A threshold exists in the 450-nm absorption to eliminate PCE decrease as color-temperature increases. • Analyze color-temperature behavior of high-performance organic photovoltaics.