Enhanced Light Harvesting in Organic Solar Cells Featuring a Biomimetic Active Layer and a Self‐Cleaning Antireflective Coating

Abstract

Advanced light manipulation is extremely attractive for applications in organic optoelectronics to enhance light harvesting efficiency. A novel method of fabricating high‐efficiency organic solar cells (OSCs) is proposed using biomimetic moth eye nanostructures in a quasi‐periodic gradient shape active layer and an antireflective coating. A 24.3% increase in photocurrent is realized without sacrificing dark electrical properties, yielding a 22.2% enhancement in power conversion efficiency to a record of 7.86% for OSCs with a poly(3‐hexylthiophene‐2,5‐diyl):indene‐C60 bis‐adduct (P3HT:ICBA) active layer. The experimental and theoretical characterizations verify that the substantial improvement of OSCs is mainly ascribed to the self‐enhanced absorption resulting from the broadband polarization‐insensitive light trapping in biomimetic nanostructured active layer, the reduction in reflectance by the antireflective coating, and surface plasmonic effect excited by corrugated metallic electrode. It is noteworthy that the pathway described here is promising for opening up opportunities to realize high‐performance OSCs towards the future photovoltaic applications.

Improvement of Stability for Small Molecule Organic Solar Cells by Suppressing the Trap Mediated Recombination

“…However, these approaches require rigid laser pulse, which is not only far away from the real operating conditions of device, but also would induce damage to the interface or 5 composed materials. Transient photocurrent (TPC) measurement is quite preferable to acquire the charge behavior related information under the real device operating conditions.…”

“…[1][2][3][4][5][6][7][8][9] Although the power conversion efficiency (PCE) has been improved greatly in the last decade, the short lifetime of OSCs hinders the residential application. It is generally accepted that the device performance degrades fast when it is exposed to oxygen and/or humid environment.…”

Nanostructures induced light harvesting enhancement in organic photovoltaics

“…Plasmonic nanostructures, such as periodic metal gratings [88][89][90], metal NPs [91][92][93][94], random corrugations [95][96][97] and biomimetic structures [98][99][100], have been investigated universally involving light concentration and manipulation in OPVs. Various kinds of plasmonic nanostructures can effectively trap light inside the photoactive layer owing to the excitation of the surface plasmonic effect, which is the collective oscillations of conductive electrons at the metal/dielectric interface.…”

“…Integrating random corrugations or biomimetic structures with quasi-periodic or random geometry in OPVs is another important and effective means to realize broadband polarization-insensitive light harvesting owing to the excitation of broadband and hybrid SPP modes, such as quasi-grating [115], deterministic aperiodic nanostructures (DANs) [116], porous nanocolumnar [100], bioinspired moth's eye nanostructures (MENs) [99,100,117] and ripple structures [118]. For instance, Tang et al have experimentally and theoretically investigated the random biomimetic structures in OPVs.…”

“…For instance, Tang et al have experimentally and theoretically investigated the random biomimetic structures in OPVs. They proposed DANs and MENs in OPVs to guide and retain light inside the active layer [99,116,117]. Moreover, they introduced the DNA and MEN structures onto the backside of glass substrates to reduce reflection losses of the incident light.…”