Plasmonic Near-Field Absorbers for Ultrathin Solar Cells

Abstract

If the active layer of efficient solar cells could be made 100 times thinner than in today's thin film devices, their economic competitiveness would greatly benefit. However, conventional solar cell materials do not have the optical capability to allow for such thickness reductions without a substantial loss of light absorption. To address this challenge, the use of plasmon resonances in metal nanostructures to trap light and create charge carriers in a nearby semiconductor material is an interesting opportunity. In this Perspective, recent progress with regards to ultrathin (∼10 nm) plasmonic nanocomposites is reviewed. Their optimal internal geometry for plasmon near-field induced absorption is discussed, and a zero thickness effective medium representation is used to optimize stacks including an Al back reflector for photovoltaics. This shows that high conversion efficiencies (>20%) are possible even when taking surface scattering effects and thin passivating layers inserted between the metal and semiconductor into account.

Nanoplasmonics: a frontier of photovoltaic solar cells

“…Such strong-absorbing direct bandgap semiconductor materials are particularly suitable for the design of the plasmonic local concentration, as the active layer is more preferable over the metal nanostructure in terms of competition for the energy absorption. It is also found through simulations that heavily damped, ultra-thin semiconductor materials such as CuInSe 2 , a-Si and organic MDMO-PPV are advantageous in the absorption competition with relatively lowly damped metal nanoparticles [47,48] . In the practical design of a PV device, the contact between the metal and the semiconductor active layer is generally unfavorable due to the increase of the recombination states at the interface, and therefore a so-called dielectric passivation layer is necessary [49,50] , which intercepts the effective overlap between the near-fi eld and the active layer.…”

“…First category is ultra-thin solar cells having highly damped active layers. The optical gain due to light concentration is much larger than the electrical loss due to recombination, resulting in an optimum barrier thickness of a few nanometers [48] . This barrier can be realized by means of coating the semiconductor with a dielectric layer or coating the metal nanostructure with a dielectric shell [51] .…”

Colloidal self-assembly concepts for light management in photovoltaics

“…Brown et al [43] Au@SiO 2 at interface TiO 2/ hole-transport layer Dye-sensitized Kawawaki et al [44] Au nanoparticle at ITO/TiO 2 interface Dye-sensitized Yoon et al [45] Ag nanoparticle at interface PEDOT:PSS/photoactive layer Organic devices [63,64]. Hence it is often desired to control the strength and range of these fields.…”

Nanophotonics silicon solar cells: status and future challenges

“…For instance, it was predicated that an ideal conversion efficiency of 18% can be achieved by combining an Ag/a-Si nanocomposite layer with an only 20-nm-thick active layer as shown in Figure 1 [54]. Experimentally, special attention needs to be paid due to the consideration from recombination loss caused by the metallic nanoparticles in the active layer.…”