High-Efficiency Nanostructured Window GaAs Solar Cells

Liang, Dong; Kang, Yangsen; Huo, Yijie; Chen, Yusi; Cui, Yi; Harris, James S.

doi:10.1021/nl402680g

Cited by 121 publications

(80 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…A nanostructured AR window layer combined with a metal mesa bar contact provides not only the enhanced light absorption of the active layers of the solar cell, but also minimizes their negative impact on the electrical properties, thus achieving 17% energy conversion efficiency for a GaAs solar cell, which is the highest reported efficiency among all III-V nanostructured solar devices. [145] By developing and implementing new device architectures in nanostructured solar cells, there can be significant improvement in light-harvesting by these materials to contribute to the conversion efficiency without accompanying electrical losses. For example, a power conversion efficiency of 13.7% was achieved for a >10 µm thick Si nanostructured solar cell, [144] and recently a record efficiency as high as 22.1% was achieved on 280 µm thick nanostructured Si solar cells using the all-backcontact concept, [9] demonstrating that it is possible to solve the Auger and surface recombination problems in nanostructured solar cells, which gives them real commercial potential.…”

Section: Wwwadvancedsciencenewscommentioning

confidence: 99%

Toward Highly Efficient Nanostructured Solar Cells Using Concurrent Electrical and Optical Design

Wang

2017

Advanced Energy Materials

View full text Add to dashboard Cite

For example, the multiple exciton generation (MEG) effect, observed in quantum dots (QDs), could have the potential to boost the Shockley-Queisser efficiency limit from 33.7% to 44.0%. [4,5] Nanostructured absorbers, featuring subwavelength features, can achieve an absorption enhancement factor higher than the conventional ray-optic limit across a broadband range of wavelengths, which opens an entirely new way of designing highly efficient nanostructured solar cells. [6,7] Meanwhile, the utilization of nanostructures can improve carrier collection by promoting the separation of photogenerated carriers and shortening the diffusion length of charge carriers using core-shell architectures. [8] However, despite the advantages of nanostructures, at present the efficiency of these solar cells remains lower than that of first-and second-generation devices. Compared with commercially available Si wafer photovoltaics, whose energy conversion efficiency can reach 25.6%, the record energy conversion efficiency of a nanostructured Si solar cell is only 22.1%, which is still far from the Shockley-Queisser efficiency limit of 32.0%. [9,10] This limited performance is due to the fact that most nanostructures bring accompanying optical or electrical losses to solar cells (Figure 1). [11][12][13][14][15] In fact, most nano-based solar cells have relatively low open-circuit voltages (V OC ) and a disproportionate enhancement of the short-circuit current density (J SC ) compared to the absorption enhancement via light-trapping nanostructures. Therefore, in order to avoid the counterbalance of optical and electrical gains by the accompanying losses associated with nanomaterials, it is necessary to look beyond singularly focused optical or electrical promotion schemes, and instead shift toward the concurrent design of electrical and optical properties using a combined perspective to achieve highly efficient nanostructured solar cells.Thus far, many excellent reviews have summarized different photon management or light-harvesting schemes with the use of nanostructures. [16][17][18][19][20][21][22][23][24] These authors point out that important work remains to ensure that improved optical absorption does not come at the sacrifice of the device's electrical properties. [16,17,[19][20][21][22][23][24] However, there have been few reviews that propose a solution for how to overcome this challenge. Recently, there has been considerable effort to increase both light absorption and the photogenerated carrier collection Recent technological advances in conventional planar and microstructured solar cell architectures have significantly boosted the efficiencies of these devices near the corresponding theoretical values. Nanomaterials and nano structures have promising potential to push the theoretical limits of solar cell efficiency even higher using the intrinsic advantages associated with these materials, including efficient photon management, rapid charge transfer, and short charge collection distances. However, at present the efficiency of...

show abstract

Section: Wwwadvancedsciencenewscommentioning

confidence: 99%

Toward Highly Efficient Nanostructured Solar Cells Using Concurrent Electrical and Optical Design

Wang

2017

Advanced Energy Materials

View full text Add to dashboard Cite

show abstract

“…[2][3][4] Different designs to enhance the efficiency have also been proposed and reported, such as the use of planer thin absorbers. [5][6][7][8][9][10][11] In order to increase the efficiency and reduce manufacturing cost by using commonly available materials with routinely achievable quality, it becomes necessary to implement light management structures (e.g., textured surface) [12][13][14] to achieve maximum absorption and minimum non-radiative recombination in a thin absorber. Our recently reported theoretical analysis of different optical designs 5,6,15,16 shows that the use of an ultra-thin (submicron) absorber and a reflective back scattering layer can potentially result in the maximal achievable conversion efficiency for single-junction GaAs solar cells.…”

Section: Introductionmentioning

confidence: 99%

Ultra-thin GaAs single-junction solar cells integrated with a reflective back scattering layer

Yang

Becker

Shi

et al. 2014

Journal of Applied Physics

View full text Add to dashboard Cite

This paper reports the proposal, design, and demonstration of ultra-thin GaAs single-junction solar cells integrated with a reflective back scattering layer to optimize light management and minimize non-radiative recombination. According to our recently developed semi-analytical model, this design offers one of the highest potential achievable efficiencies for GaAs solar cells possessing typical non-radiative recombination rates found among commercially available III-V arsenide and phosphide materials. The structure of the demonstrated solar cells consists of an In0.49Ga0.51P/GaAs/In0.49Ga0.51P double-heterostructure PN junction with an ultra-thin 300 nm thick GaAs absorber, combined with a 5 μm thick Al0.52In0.48P layer with a textured as-grown surface coated with Au used as a reflective back scattering layer. The final devices were fabricated using a substrate-removal and flip-chip bonding process. Solar cells with a top metal contact coverage of 9.7%, and a MgF2/ZnS anti-reflective coating demonstrated open-circuit voltages (Voc) up to 1.00 V, short-circuit current densities (Jsc) up to 24.5 mA/cm2, and power conversion efficiencies up to 19.1%; demonstrating the feasibility of this design approach. If a commonly used 2% metal grid coverage is assumed, the anticipated Jsc and conversion efficiency of these devices are expected to reach 26.6 mA/cm2 and 20.7%, respectively.

show abstract

“…Compared to planar cell architectures, nanopillars can enhance light absorption and improve carrier collection, thereby requiring less material and tolerating lower material quality. [1][2][3][4][5][6] However, increased non-radiative surface recombination associated with their large surface area often compensates performance gains and explains why, as of today, nanopillar solar cells have not yet been able to outperform their planar counterparts. [ 7 ] In contrast to other III-V semiconductors, untreated InP possesses a relatively low surface recombination velocity, [ 8 ] which makes it an ideal material system for large surface-area nanopillar devices.…”

Section: Introductionmentioning

confidence: 99%

Enhanced Near‐Bandgap Response in InP Nanopillar Solar Cells

Battaglia

Zheng

et al. 2014

Advanced Energy Materials

View full text Add to dashboard Cite

the performance of photocathodes for solar hydrogen production. [ 9 ] Compared to a planar reference, the implementation of nanopillars improved both photocurrent and onset potential, but the exact mechanism for this improvement remained unclear.Here we investigate the effect of nanopillar texturing on the performance of InP solar cells. On the optical level, nanopillars minimize the refl ectance over a broad spectral range. Mapping the current generated by an electron beam across the cell cross-section, we further show that texturing increases the effective minority carrier collection length leading to improved photocurrent and open-circuit voltage and a power conversion effi ciency of 14.4%. Results and DiscussionNanopillars are fabricated via maskless, lithography-free reactive ion etching (RIE). The entire device fabrication avoids the use of expensive metal-organic precursor gases necessary for the fabrication of III-V solar cells via traditional chemical vapor deposition. In addition, we recently introduced a thinfi lm vapor-liquid-solid growth technique for the growth of high-quality InP thin fi lms (1-3 µm) on cheap non-epitaxial substrates, [ 10 ] enabling future elimination of the thick (350 µm) expensive InP wafers used in this work which, together with the precursor gases, represent the dominant cost drivers for III-V photovoltaics. [ 11 ] A sketch of the fabrication fl ow is shown in Figure 1 a. Zndoped p-type InP wafers with a carrier density of 3 × 10 17 cm −3 are etched in hydrochloric (HCl) acid (6%) for 30 s to remove the native oxide. An ohmic backcontact is formed by sputtering a thin layer of Zn (20 nm) capped with a Au layer (100 nm) and subsequent annealing at 420 °C in forming gas (H 2 :N 2 = 5%) for 45 min. The front side is wet etched again in HCl (6%) and dry etched in a H 2 :CH 4 :Ar plasma (40 sccm: 10 sccm: 10 sccm) at a pressure of 110 mTorr, a power density of 0.5 W cm −2 and a bias voltage of 500-550 V to form the nanopillars. Following oxidation in a O 2 plasma [ 12 ] and etching in HCl (3%) for 30 s to remove undesired metallic indium residues and the defective InP layer (see discussion below) formed during the RIE process at the pillar surface, a conformal transparent conductive indium tin oxide electrode (ITO, In 2 O 3 :SnO = 90%:10%, 35 nm) is deposited by RF sputtering at room temperature atThe effect of nanopillar texturing on the performance of InP solar cells is investigated. Maskless, lithography-free reactive ion etching of InP nanopillars improves the open-circuit voltage, reduces refl ectance over a broad spectral range, and enhances the near-bandgap response compared to a fl at, non-textured cell with comparable refl ectance in the infrared. Electron-beam induced current measurements indicate an increased effective minority carrier collection length. The response at short wavelengths decreases due to the formation of a defective surface layer with strong non-radiative recombination. Plasma oxidation and wet etching partially restore the blue response resulting in a ...

show abstract

High-Efficiency Nanostructured Window GaAs Solar Cells

Cited by 121 publications

References 30 publications

Toward Highly Efficient Nanostructured Solar Cells Using Concurrent Electrical and Optical Design

Toward Highly Efficient Nanostructured Solar Cells Using Concurrent Electrical and Optical Design

Ultra-thin GaAs single-junction solar cells integrated with a reflective back scattering layer

Enhanced Near‐Bandgap Response in InP Nanopillar Solar Cells

Contact Info

Product

Resources

About