Material Design and Device Fabrication Strategies for Stretchable Organic Solar Cells

Abstract

Recent advances in the power conversion efficiency (PCE) of organic solar cells (OSCs) have greatly enhanced their commercial viability. Considering the technical standards (e.g., mechanical robustness) required for wearable electronics, which are promising application platforms for OSCs, the development of fully stretchable OSCs (f‐SOSCs) should be accelerated. Here, a comprehensive overview of f‐SOSCs, which are aimed to reliably operate under various forms of mechanical stress, including bending and multidirectional stretching, is provided. First, the mechanical requirements of f‐SOSCs, in terms of tensile and cohesion/adhesion properties, are summarized along with the experimental methods to evaluate those properties. Second, essential studies to make each layer of f‐SOSCs stretchable and efficient are discussed, emphasizing strategies to simultaneously enhance the photovoltaic and mechanical properties of the active layer, ranging from material design to fabrication control. Key improvements to the other components/layers (i.e., substrate, electrodes, and interlayers) are also covered. Lastly, considering that f‐SOSC research is in its infancy, the current challenges and future prospects are explored.

Sequentially regular polymer acceptors featuring flexible spacers for high-performance and mechanically robust all-polymer solar cells

“…The IS all-PSC has a device platform in which all the consisting layers are stretchable in every direction, which can be distinguished from previously reported flexible PSCs or other structurally engineered stretchable PSCs. 9–12 We incorporated TPU as a stretchable substrate, and used organic ( i.e. , PEDOT:PSS) and liquid-metal ( i.e.…”

“…To this end, intrinsically stretchable (IS) PSCs have been recently reported, in which all the consisting layers are stretchable in every direction. 9–13 For IS-PSCs, the use of conventional small-molecule-acceptor (SMA)-based active layers often suffers from poor tensile properties, showing rapid degradation of the initial power conversion efficiency (PCE) during stretching.…”

Design of Dithienopyran-Based Conjugated Polymers for High-Performance Electrochromic Devices

“…In recent decades, electrochromic devices (ECDs) have been intensively studied for their several applications including smart windows, functional energy storage devices, camouflage devices, heat shutters, and information displays. − In particular, conjugated polymer-based ECDs have been considered advantageous platforms over inorganic chromophore-based systems due to their wide color tunability, solution processability, and intrinsic flexibility/stretchability. − In this context, many promising electrochromic polymers (ECPs) have been proposed. However, most studies have focused on achieving various colors and improving optical contrast and cycling stability. − …”

Efficient Semitransparent Organic Solar Cells with Highly Transparent Metal Front Electrodes

“…Organic solar cells (OSCs) have been considered as a promising green energy technology due to their advantages in solution processability, biocompatibility, light weight, and semitransparency. − Semitransparent OSCs (STOSCs) exhibit great potential for electricity-generating windows, self-powered greenhouses, and vehicle-integrated and building-integrated photovoltaics, − with their tunable absorption spectrum and rapidly improved power conversion efficiencies (PCEs). , PCE and average visible transmittance (AVT) are two key parameters to evaluate the performance of STOSCs. PCE is the portion of energy in the form of sunlight that can be converted via photovoltaics into electricity by the solar cell.…”

“…The chemical structures and HOMO/LOMO levels of PBDTTT-EFT and IEICO-4F are shown in Figure a. The HOMO/LUMO levels of PBDTTT-EFT and IEICO-4F are −4.81/–2.72 and −5.14/–3.40 eV, respectively . The offset between the HOMO level of PBDTTT-EFT and the LUMO level of IEICO-4F is 1.41 eV, which should contribute to a relatively large V OC .…”