High-efficiency, broad-band and wide-angle optical absorption in ultra-thin organic photovoltaic devices

Abstract

Metal nanogratings as one of the promising architectures for effective light trapping in organic photovoltaics (OPVs) have been actively studied over the past decade. Here we designed a novel metal nanowall grating with ultra-small period and ultra-high aspect-ratio as the back electrode of the OPV device. Such grating results in the strong hot spot effect in-between the neighboring nanowalls and the localized surface plasmon effect at the corners of nanowalls. These combined effects make the integrated absorption efficiency of light over the wavelength range from 400 to 650 nm in the active layer for the proposed structure, with respect to the equivalent planar structure, increases by 102% at TM polarization and by 36.5% at the TM/TE hybrid polarization, respectively. Moreover, it is noted that the hot spot effect in the proposed structure is more effective for ultra-thin active layers, which is very favorable for the exciton dissociation and charge collection. Therefore such a nanowall grating is expected to improve the overall performance of OPV devices.

Ultra-Thin Organic Solar Cells Incorporating Dielectric-Coated Comb Silver Nanogratings

“…The refractive indices of all other materials are extracted from Ref. [25]. The integrated absorption efficiency (A int ) of active layer is calculated by integrating the absorption over the wavelength range from 400 to 650 nm.…”

“…In our recent work [25], we have demonstrated the potential of short-pitch plasmonic gratings in enhancing the light absorption of OSCs. Following that work, here, we will theoretically investigate the effect of coating engineering on the absorption performance of the plasmonic incorporated OSCs.…”

Omnidirectional and broadband optical absorption enhancement in small molecule organic solar cells by a patterned MoO3/Ag/MoO3 transparent anode

“…For this purpose, different approaches, including incorporating periodic metallic gratings in thin OSCs, have been reported [2][3][4]. Metallic gratings increasing the light absorption of active layer in OSCs is attributed to the enhanced field due to the excitation of surface plasmon resonances in the form of propagating surface plasmon polaritons (SPPs) and localized surface plasmons (LSPs) [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. In general, due to the polarization dependence of one-dimensional (1D) nanograting, the light trapping is only effective for transverse magnetic (TM) polarization with the magnetic component parallel to 1D nanogratings.…”

“…In general, due to the polarization dependence of one-dimensional (1D) nanograting, the light trapping is only effective for transverse magnetic (TM) polarization with the magnetic component parallel to 1D nanogratings. While for transverse electric (TE) polarization with the electric component parallel to 1D nanogratings, 1D metallic grating often results in suppression in optical absorption [4][5][6][7][8]. For example, Min et al [6] introduced a top transparent PEDOT electrode partially substituted by a periodic silver grating into CuPc/PTCBI-based solar cell to excite plasmonic modes.…”

Improved performances of CuPc/C60-based solar cell by using randomly and irregularly embossed PEDOT:PSS as anode buffer layer

“…However, the incident photons could not be absorbed efficiently within thin active layers. A highly promising strategy toward improving optical absorption of active layer without increasing its thickness is to employ periodic nanostructured electrode or buffer layer [8][9][10][11][12][13][14][15][16]. Conventionally, periodic nanostructures can be fabricated by various lithography-based techniques [11][12][13][14].…”