Macroporous silicon as an absorber for thin heterojunction solar cells

Brendel, Rolf; Ferré, R.; Harder, Nils‐Peter; Kajari‐Schröder, Sarah

doi:10.1109/pvsc.2012.6317781

Cited by 3 publications

(2 citation statements)

References 24 publications

(26 reference statements)

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“…To counter these side effects, advanced fabrication methods, the introduction of molecular barriers, and photon management to maximize light absorption at nanoscale will be needed. The introduction of macropores into photovoltaic devices has already been 29 Carrier lifetimes were enhanced by passivation of pore walls with a thermally grown oxide layer.…”

Section: δ = + E E Ir 0 Cellmentioning

confidence: 99%

Minimization of Ionic Transport Resistance in Porous Monoliths for Application in Integrated Solar Water Splitting Devices

et al. 2016

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Monolithic solar water splitting devices consist of photovoltaic materials integrated with electrocatalysts and produce solar hydrogen by water splitting upon solar illumination in one device. Upscaling of monolithic solar water splitting devices is obstructed by high ohmic losses in the electrolyte due to long ionic transport distances. A new design overcomes the problem by introducing micron sized pores in a silicon wafer substrate coated with electrocatalysts. A porous solar hydrogen device was simulated by applying a current corresponding to ca. 10% solar-to-hydrogen efficiency. Porous monoliths of 550 μm thickness with varying pore size and spacing were fabricated by laser ablation and electrochemically characterized. Ohmic losses well below 100 mV were reached at 14.4% porosity with 77 μm pores spaced 250 μm apart in 0.25 M KOH electrolyte. In 1 M KOH, 100 mV was reached at 6% porosity with 1 mm pore spacing. Our results suggest ohmic losses below 50 mV can be achieved when using 10 μm thick substrates at 0.2% porosity. These findings make it possible for monolithic solar water splitting devices to be scaled without loss of efficiency. ■ INTRODUCTIONHydrogen is one of the promising energy vectors that will likely be part of the future sustainable energy portfolio. 1 Using sunlight to split water into hydrogen and oxygen is a viable option for solar hydrogen production and several technologies exist that achieve water splitting at high efficiency. 2 A direct way to produce solar hydrogen is by using a solar water splitting device which combines light absorption, charge separation and electrochemical reactions in an integrated device. 3 High solarto-hydrogen (STH) efficiencies are reached using high-end photovoltaics (PV) coupled to electrocatalysts submerged in concentrated aqueous electrolyte. 4−7 The use of robust earthabundant catalysts and stable light absorbing materials with suitable band gaps has also been demonstrated. 8−11 These approaches show great promise at lab scale and development of practical systems is ongoing. 12−16 Beside the performance of catalysts and light absorbers, cell design is important and ohmic losses need to be minimized to maximize overall efficiency. 17,18 There are two common design types. 19,20 In the "wired" design ( Figure 1A) planar anode and cathode have opposed surfaces at close proximity such that the interelectrode distance to be covered by ions in the liquid electrolyte is minimized. 9−11 The "wireless" or "monolithic" layout ( Figure 1B) simplifies cell design by eliminating electrical contacts and wires through integration of all components in a monolithic flat assembly. 10

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Section: δ = + E E Ir 0 Cellmentioning

confidence: 99%

Minimization of Ionic Transport Resistance in Porous Monoliths for Application in Integrated Solar Water Splitting Devices

et al. 2016

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“…For mesoporous silicon, a highly concentrated HF solution (19.5 mol L −1 ) was used, containing ethanol as a surface wetting agent [5]. Macroporous silicon was prepared with a low-concentrated HF solution (1.5 mol L −1 ) in the presence of the surface wetting agent acetic acid [6]. Both etching processes are driven electrochemically and, therefore, do not need an additional oxidizing agent.…”

Section: Introductionmentioning

confidence: 99%

Analysis methods for meso- and macroporous silicon etching baths

2012

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Analysis methods for electrochemical etching baths consisting of various concentrations of hydrofluoric acid (HF) and an additional organic surface wetting agent are presented. These electrolytes are used for the formation of meso- and macroporous silicon. Monitoring the etching bath composition requires at least one method each for the determination of the HF concentration and the organic content of the bath. However, it is a precondition that the analysis equipment withstands the aggressive HF. Titration and a fluoride ion-selective electrode are used for the determination of the HF and a cuvette test method for the analysis of the organic content, respectively. The most suitable analysis method is identified depending on the components in the electrolyte with the focus on capability of resistance against the aggressive HF.

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Porous silicon solar cells

Balucani

Kholostov

Varlamava

et al. 2015

2015 IEEE 15th International Conference on Nanotechnology (IEEE-NANO)

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We developed a new process for the fabrication of crystalline solar cell, based on an ultrathin silicon membrane, taking advantage of porous silicon technology. The suggested architecture allows the costs reduction of silicon based solar cell reusing the same wafer to produce a great number of membranes. The architectures combines the efficiency of crystalline silicon solar cell, with the great absorption of porous silicon, and with a more efficient way to use the material. The new process faces the main challenge to achieve an effective and not expensive passivation of the porous silicon surface, in order to achieve an efficient photovoltaic device. At the same time the process suggests a smart way to selective doping of the macroporous silicon layers despite the through-going pores.

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Macroporous silicon as an absorber for thin heterojunction solar cells

Cited by 3 publications

References 24 publications

Minimization of Ionic Transport Resistance in Porous Monoliths for Application in Integrated Solar Water Splitting Devices

Minimization of Ionic Transport Resistance in Porous Monoliths for Application in Integrated Solar Water Splitting Devices

Analysis methods for meso- and macroporous silicon etching baths

Porous silicon solar cells

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