Color-neutral, semitransparent organic photovoltaics for power window applications

Abstract

Semitransparent organic photovoltaic cells (ST-OPVs) are emerging as a solution for solar energy harvesting on building facades, rooftops, and windows. However, the trade-off between power-conversion efficiency (PCE) and the average photopic transmission (APT) in color-neutral devices limits their utility as attractive, power-generating windows. A color-neutral ST-OPV is demonstrated by using a transparent indium tin oxide (ITO) anode along with a narrow energy gap nonfullerene acceptor near-infrared (NIR) absorbing cell and outcoupling (OC) coatings on the exit surface. The device exhibits PCE = 8.1 ± 0.3% and APT = 43.3 ± 1.2% that combine to achieve a light-utilization efficiency of LUE = 3.5 ± 0.1%. Commission Internationale d’eclairage chromaticity coordinates of (0.38, 0.39), a color-rendering index of 86, and a correlated color temperature of 4,143 K are obtained for simulated AM1.5 illumination transmitted through the cell. Using an ultrathin metal anode in place of ITO, we demonstrate a slightly green-tinted ST-OPV with PCE = 10.8 ± 0.5% and APT = 45.7 ± 2.1% yielding LUE = 5.0 ± 0.3% These results indicate that ST-OPVs can combine both efficiency and color neutrality in a single device.

Latest Progress on Photoabsorbent Materials for Multifunctional Semitransparent Organic Solar Cells

“…[ 57,67 ] Based on the report by Li et al. [ 67 ] and Forrest and co‐workers, [ 68 ] despite the superior PCE > 9% of the recent ST‐OSCs incorporating efficient new photovoltaic materials, most of these photovoltaic cells displayed AVT ≈ 30%, leading to LUE < 4.0%, suggesting a superior trade‐off between PCE and AVT is desirable to further improve LUE in the devices.…”

“…Likewise, Forrest and co‐workers independently also reported ACS8 (named as A078). [ 68 ] To understand the effect of alkylthio‐alkyl side chains, the authors compared the absorption spectra of A078 (with partially fused core) with its fully fused counterpart SBT‐FIC. Surprisingly, A078 showed much remarkable bathochromic shift with compact molecular packing than SBT‐FIC, thus signifying that noncovalent S⋅⋅⋅S interactions can facilitate the planarization and rigidification of π‐conjugated structure, leading to narrowing of E g .…”

“…As a result, the development of new transparent electrodes and, hole transport and electron transport layer with favorable optoelectronic, flexibility and processing properties should be explored further. 6)In most of the previous reports, photovoltaic performances and AVT in ST‐OSCs are discussed alone. As reported by Hou and co‐workers [ 68 ] more unified measuring standards like light utilization efficiency (LUE) = performance × average photopic transmission (APT) must be implemented to accurately appraise the true potentials of ST‐OSCs for practical applications. 7)Lastly, the cutting edge‐multifunctional ST‐OSCs field is yet in the initial stage and its device structure and requirement of the photoabsorbent layer will be dependent on the requirement of different scenarios. Table 4 recapitulates the benefits, current challenges, and future directions for multifunctional ST‐OSCs.…”

High‐Performance Semi‐Transparent Organic Photovoltaic Devices via Improving Absorbing Selectivity

“…[32][33][34] In the most recent, the A078 based ST-OPV further boosted the single junction ST-OPV to a record high LUE of 5.0% by sacrificing the CRI. [35] Besides the photo-active layer, light absorbing selectivity of ST-OPV can also be affected by the device structure. An ST-OPV device typically involves multiple photo-inactive layers, and the parasitic absorption of which reduces the absorbing selectivity of a device by either decreasing the light transmittance in visible regions or hindering the light harvest in invisible regions.…”

Semi-Transparent Organic Photovoltaic Cells with Dielectric/Metal/Dielectric Top Electrode: Influence of the Metal on Their Performances

“…More specifically, semi-transparent OPVs attract strong interest due to the efforts currently directed toward building integrated photovoltaics (BIPVs). Recently, much research has focused on improving OPV efficiency [1][2][3][4], but some applications, such as BIPV, induce the use of semi-transparent OPVs, which are less efficient than the usual opaque OPVs because they have to transmit a significant amount of visible light [5,6]. Therefore, for semi-transparent OPVs, it is not appropriate to use optimal organic layer thickness.…”