High-Performance Nonfullerene Organic Photovoltaics Applicable for Both Outdoor and Indoor Environments through Directional Photon Energy Transfer

Abstract

With the advent of the smart factory and the Internet of Things (IoT) sensors, organic photovoltaics (OPVs) gained attention because of their ability to provide indoor power generation as an off-grid power supply. To satisfy these applications, OPVs must be capable of power generation in both outdoor and indoor at the same time for developing environmentally independent devices. For high performances in indoor irradiation, a strategy that maximizes photon utilization is essential. In this study, graphene quantum dots (GQDs), which have unique emitting properties, are introduced into a ZnO layer for efficient photon utilization of nonfullerene-based OPVs under indoor irradiation. GQDs exhibit high absorption properties in the 350–550 nm region and strong emission properties in the visible region due to down-conversion from lattice vibration. Using these properties, GQDs provide directional photon energy transfer to the bulk-heterojunction (BHJ) layer because the optical properties overlap. Additionally, the GQD-doped ZnO layer enhances shunt resistance (R Sh) and forms good interfacial contact with the BHJ layer that results in increased carrier dissociation and transportation. Consequently, the fabricated device based on P­(Cl-Cl)­(BDD = 0.2) and IT-4F introduces GQDs exhibiting a maximum power conversion efficiency (PCE) of 14.0% with a superior enhanced short circuit current density (J SC) and fill factor (FF). Furthermore, the fabricated device exhibited high PCEs of 19.6 and 17.2% under 1000 and 200 lux indoor irradiation of light emitting diode (LED) lamps, respectively.

An Overview of High‐Performance Indoor Organic Photovoltaics

“…Under indoor LED illumination of 1000 lx, the devices with doped ZnO exhibited an excellent PCE of 19.6 %, outperforming the devices based on pristine ZnO (17.2 %). [50] Ma et al investigated the effect of different ETLs on the performance of IOPV devices. Both in PM6:Y6-O and P3TEA: FTTB-PDI4 systems, the devices with ((N,N-dimethyl-ammonium N-oxide)propyl perylene diimide) (PDINO) and commonly used poly[(9, 9-bis (3'-(N,N-dimethylamino) propyl)-2, 7-fluorene)-alt-2, 7-(9, 9-dioctylfluorene)] (PFN) as ETLs showed comparable PCE under the illumination of AM 1.5G.…”

“…Reproduced with permission. [50] Copyright 2020, American Chemical Society. (g) Energy level of the materials systems.…”

“…(e) Absorption properties and (f) emission properties of pristine ZnO film, GQDs-doped ZnO film [absorption property of GQDs is shown in (e)]. Reproduced with permission [50]. Copyright 2020, American Chemical Society.…”

Optimizing the Photovoltaic Performance of Organic Solar Cells for Indoor Light Harvesting

“…[15] However, for indoor applications, the performance of the OSCs would benefit less from the broad absorption spectra of low bandgap acceptors, since the spectra range of indoor illumination is usually limited to 400 to 700 nm. [16][17][18] On the other hand, the use of the low bandgap NFAs leads to significant voltage losses, limiting the photovoltage of the solar cells under indoor light illumination, according to the Shockley-Queisser theory. [19,20] In this regard, larger bandgap acceptors are better suited for OSCs for being used for indoor applications.…”

Ultra-Flexible Organic Solar Cell Based on Indium-Zinc-Tin Oxide Transparent Electrode for Power Source of Wearable Devices

“…Fourth, the fabricated device must have excellent mechanical stability [15,16]. Currently, indium-tin oxide (ITO) transparent electrodes are being applied to various optoelectronic devices, such as liquid crystal displays (LCDs), organic light-emitting diodes (OLEDs), organic photovoltaics (OPVs), and perovskite solar cells due to their excellent transmittance and conductivity [17][18][19][20]. However, in order to improve the electro-optical properties of ITO, a thermal treatment process of 300 • C or higher is required, which makes it difficult to apply to organic-based ultra-flexible substrates [21].…”