Toward Efficient and Omnidirectional n-Type Si Solar Cells: Concurrent Improvement in Optical and Electrical Characteristics by Employing Microscale Hierarchical Structures

Abstract

We demonstrated that hierarchical structures combining different scales (i.e., pyramids from 1.5 to 7.5 μm in width on grooves from 40 to 50 μm in diameter) exhibit excellent broadband and omnidirectional light-trapping characteristics. These microscaled hierarchical structures could not only improve light absorption but prevent poor electrical properties typically observed from nanostructures (e.g., ultra-high-density surface defects and nonconformal deposition of following layers, causing low open-circuit voltages and fill factors). The microscaled hierarchical Si heterojunction solar cells fabricated with hydrogenated amorphous Si layers on as-cut Czochralski n-type substrates show a high short-circuit current density of 36.4 mA/cm(2), an open-circuit voltage of 607 mV, and a conversion efficiency of 15.2% due to excellent antireflection and light-scattering characteristics without sacrificing minority carrier lifetimes. Compared to cells with grooved structures, hierarchical heterojunction solar cells exhibit a daily power density enhancement (69%) much higher than the power density enhancement at normal angle of incidence (49%), demonstrating omnidirectional photovoltaic characteristics of hierarchical structures. Such a concept of hierarchical structures simultaneously improving light absorption and photocarrier collection efficiency opens avenues for developing large-area and cost-effective solar energy devices in the industry.

2D-MoS2 nanosheets as effective hole transport materials for colloidal PbS quantum dot solar cells

“…For the commercial viability of solar cell devices, it is of great importance to develop materials with ease of synthesis, costeffective device building and high throughput performance. This can be achieved by either further improvement in the solar cell efficiency 26,27 or reducing the cost 28,29 of the devices or both. Silicon based solar cells have dominated the photovoltaic industry due to their abundance, high performance and mature processing technology.…”

Omnidirectional Harvesting of Weak Light Using a Graphene Quantum Dot-Modified Organic/Silicon Hybrid Device

“…19 For photovoltaic devices, researchers have applied various photon management techniques that enable omnidirectional and weak light harvesting, such as hierarchical surface engineering, graded refractive index antireflective coatings, and the employment of colloidal nanospheres or periodic nanopillar 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 8 arrays. [20][21][22][23][24] However, these omnidirectional light-harvesting methods are often achieved using complex fabrication processes, which usually come with unwanted defects, recombination sites, and contaminations that deteriorate the deviceʼs performance and thus require additional treatment procedures. [20][21][22][23][24] To overcome these issues, we need to develop simpler techniques, such as solution processing, to construct devices that enable omnidirectional harvesting of light under outdoor and indoor low-light conditions.…”

“…[20][21][22][23][24] However, these omnidirectional light-harvesting methods are often achieved using complex fabrication processes, which usually come with unwanted defects, recombination sites, and contaminations that deteriorate the deviceʼs performance and thus require additional treatment procedures. [20][21][22][23][24] To overcome these issues, we need to develop simpler techniques, such as solution processing, to construct devices that enable omnidirectional harvesting of light under outdoor and indoor low-light conditions. Recently, we used GQD-poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) to increase the surface morphology, conductivity, and electrocatalytic activity in Pt-free dye-sensitized solar cells for achieving weak-light light harvesting.…”

Passivation of high aspect ratio silicon nanowires by using catalytic chemical vapor deposition for radial heterojunction solar cell application

“…Plasma enhanced chemical vapor deposition (PECVD), a mature thin lm deposition technology widely used in commercial industry, is commonly adopted to deposit silicon thin lms. Reported V oc and conversion efficiency of RJ-HET solar cells continuously improved and exceeded RJ-HOMO solar cells 14,15 in a short time. However, interface and growth layers have to experience ion bombardment during PECVD process, thus surface damage is unavoidable.…”