A Bifunctional Copolymer Additive to Utilize Photoenergy Transfer and To Improve Hole Mobility for Organic Ternary Bulk-Heterojunction Solar Cell

To realize the high efficiency organic photovoltaics (OPVs), two critical requirements have to be fulfilled: (1) increasing the photon energy absorption range of the active layer, and (2) improving charge separation and transport in the active layer. This study reports the utilization of THC8, a novel fluorescence-based polymer containing propeller-shaped di-triarylamine and fluorene moieties in the active layer consisting of poly-3-hexylthiophene and [6,6]-phenyl-C61-butyric acid methyl ester to form a ternary bulk heterojunction. The results showed that the high absorbance and strong fluorescence of THC8 at 420 and 510 nm, respectively, broadened the spectral absorption of the OPV, possibly through Förster resonance energy transfer. In addition, the morphology of the device active layer was improved with the addition of a suitable amount of THC8. Consequently, the charge transport property of the active layer was improved. The best power conversion efficiency (PCE) of the device with THC8 was 3.88%, a 25% increase compared to the PCE of a pristine OPV

Performance Characterization of Dye-Sensitized Photovoltaics under Indoor Lighting

Indoor utilization of emerging photovoltaics is promising; however, efficiency characterization under room lighting is challenging. We report the first round-robin interlaboratory study of performance measurement for dye-sensitized photovoltaics (cells and mini-modules) and one silicon solar cell under a fluorescent dim light. Among 15 research groups, the relative deviation in power conversion efficiency (PCE) of the samples reaches an unprecedented 152%. On the basis of the comprehensive results, the gap between photometry and radiometry measurements and the response of devices to the dim illumination are identified as critical obstacles to the correct PCE. Therefore, we use an illuminometer as a prime standard with a spectroradiometer to quantify the intensity of indoor lighting and adopt the reverse-biased current–voltage (<i>I</i>–<i>V</i>) characteristics as an indicator to qualify the <i>I</i>–<i>V</i> sampling time for dye-sensitized photovoltaics. The recommendations can brighten the prospects of emerging photovoltaics for indoor applications