Investigation of Quantum Size Effects on the Optical Absorption in Ultrathin Single Quantum Well Solar Cell Embedded as a Nanophotonic Resonator

Meddeb, Hosni; Götz‐Köhler, Maximilian; Osterthun, Norbert; Sergeev, Oleg; Gehrke, Kai; Vehse, Martin; Agert, Carsten

doi:10.1109/jphotov.2022.3150726

Cited by 5 publications

(20 citation statements)

References 62 publications

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“…[261] As can be seen in Figure 4e, showing a photograph of a-Ge QWSC with a 2 nm-thick QW, quasi-total absorption was achieved in the opaque mode, owing to the enhanced absorption under photonic confinement. [262] Whereas, the thickness reduction promoted the light transmission through the areas without back contact. This would be beneficial for semitransparent devices.…”

Section: Bandgap Tuning In Single Junction Sc Technologiesmentioning

confidence: 99%

“…It is demonstrated that such selection process should be performed based on the concept of spectral efficiency η (λ), wavelength-resolved efficiency. [262] In order to realize a tandem combination with significant boost in performance compared to single junction c-Si, both, appropriate bandgap of the top cell and high efficiency conditions are desired. The maximum efficiency of a tandem configuration is determined as a sum of the integrated subcell spectral efficiencies weighted by the corresponding spectrum range and normalized to the incident photon power [275] Figure 5.…”

Section: Bandgap Tuning In Multijunction Sc Technologies With Tandem ...mentioning

confidence: 99%

“…It is demonstrated that such selection process should be performed based on the concept of spectral efficiency η (λ), wavelength‐resolved efficiency. [ 262 ] In order to realize a tandem combination with significant boost in performance compared to single junction c‐Si, both, appropriate bandgap of the top cell and high efficiency conditions are desired. The maximum efficiency of a tandem configuration is determined as a sum of the integrated subcell spectral efficiencies weighted by the corresponding spectrum range and normalized to the incident photon power [ 275 ]

\begin{array}{*{20}{c}}{{\eta _{{\rm{tandem}}}} = \frac{{\smallint {\eta _{{\rm{top}}}}\left( \lambda \right)I\left( \lambda \right)d\lambda \frac{{{\phi _{{\rm{top}}}}\left( \lambda \right)}}{{{\phi _{{\rm{incident}}}}\left( \lambda \right)}}}}{{\smallint I\left( \lambda \right)d\lambda }} + \frac{{\smallint {\eta _{{\rm{buttom}}}}\left( \lambda \right)I\left( \lambda \right)d\lambda \frac{{{\phi _{{\rm{buttom}}}}\left( \lambda \right)}}{{{\phi _{{\rm{incident}}}}\left( \lambda \right)}}}}{{\smallint I\left( \lambda \right)d\lambda }}}\end{array}

where ϕ is the photon flux, I (λ) the spectral irradiance (in W m −2 nm −1 ), λ the wavelength.…”

Section: State Of the Art Of Tunable Solar Cell Technologiesmentioning

confidence: 99%

See 2 more Smart Citations

Tunable Photovoltaics: Adapting Solar Cell Technologies to Versatile Applications

Meddeb

Götz‐Köhler

Neugebohrn

et al. 2022

Advanced Energy Materials

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solar, wind, hydro, geothermal, and biomass, to enable a steady mitigation of greenhouse gas emissions, which are causing the planetary climate change and global warming. [5][6][7] Additionally, due to the economic development and the worldwide urbanization, a continuous rise of the global energy consumption across all key sectors, that is, power, heating, industry, and transport is occurring. This is expressed by an increase in the annual global electricity demand by 4.5% in 2021 corresponding to additional 1000 TWh. [4] Hence, strict criteria for the selection of competitive and abundant energy alternatives are imposed, requiring high yield at affordable prices. [8] The share of total renewables power generation excluding hydropower exceeded 3000 TWh in 2020, corresponding to almost 12% of the global electricity generation. [3] Considering an effective synergy between various sustainable energy candidates, solar photovoltaics (PV) have demonstrated great capabilities that can satisfy the requirements in the pathway towards 100% renewable electricity. [9][10][11][12] Owing to the research and development activities over the last decades, the power conversion efficiencies of solar cells (SC) have skyrocketed with a prolonged operation lifetime (>15 years) and a drastic plummeting in manufacturing costs (global average module selling price below $0.25 per W). [6,[13][14][15] The rapid universal deployment of PV resulted in a contribution of about 3.4% in the worldwide electricity generation in 2020. [3] Presently, the global installed PV capacity is approaching 1 TW and it is envisioned to reach ≈10 TW by 2030 and 30 to 70 TW by 2050. [16] Interestingly, along with massive electricity production using conventional solar power plants and rooftop solar panels, ancillary concepts of PV offer new strategies for supplying modern systems in versatile applications. [17][18][19] Moreover, diverse functionalities beyond solar energy harvesting can be afforded by adaptive PV, including aesthetic appearance, visual comfort and thermal management. [17,18,20,21] The distributed nature and the ubiquitous accessibility of multifunctional PV products are substantial features of solar PV in contrast to other renewable energies. However, traditional SCs dominating the market impose intrinsic optoelectronic and thermomechanical limitations, that prohibit their multifunctional utilization. To overcome these drawbacks, novel functional materials and innovative device architecture Solar photovoltaics (PV) offer viable and sustainable solutions to satisfy the growing energy demand and to meet the pressing climate targets. The deployment of conventional PV technologies is one of the major contributors of the ongoing energy transition in electricity power sector. However, the diversity of PV paradigms can open different opportunities for supplying modern systems in a wide range of terrestrial, marine, and aerospace applications. Such ubiquitous and versatile applications necessitate the development of PV technologies with customized desig...

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Section: Bandgap Tuning In Single Junction Sc Technologiesmentioning

confidence: 99%

Section: Bandgap Tuning In Multijunction Sc Technologies With Tandem ...mentioning

confidence: 99%

\begin{array}{*{20}{c}}{{\eta _{{\rm{tandem}}}} = \frac{{\smallint {\eta _{{\rm{top}}}}\left( \lambda \right)I\left( \lambda \right)d\lambda \frac{{{\phi _{{\rm{top}}}}\left( \lambda \right)}}{{{\phi _{{\rm{incident}}}}\left( \lambda \right)}}}}{{\smallint I\left( \lambda \right)d\lambda }} + \frac{{\smallint {\eta _{{\rm{buttom}}}}\left( \lambda \right)I\left( \lambda \right)d\lambda \frac{{{\phi _{{\rm{buttom}}}}\left( \lambda \right)}}{{{\phi _{{\rm{incident}}}}\left( \lambda \right)}}}}{{\smallint I\left( \lambda \right)d\lambda }}}\end{array}

where ϕ is the photon flux, I (λ) the spectral irradiance (in W m −2 nm −1 ), λ the wavelength.…”

Section: State Of the Art Of Tunable Solar Cell Technologiesmentioning

confidence: 99%

See 1 more Smart Citation

Tunable Photovoltaics: Adapting Solar Cell Technologies to Versatile Applications

Meddeb

Götz‐Köhler

Neugebohrn

et al. 2022

Advanced Energy Materials

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“…These spatial confinement conditions promote the coupling between photons and confined charge carriers. 26 High parasitic absorption can be noticed within the carrierselective contact regions, in particular on the front side, which suggests a favourable replacement with wide-bandgap metal oxides to enhance both the photocurrent and the transparency of such QWbased ST-PV. 9,10 Another important specification of our semitransparent QW PV technology is the angle insensitive behaviour of the absorbing resonance in the optical nanocavity.…”

Section: Optical Modelling Of Semi-transparent Ultrathin Si/ge Mqw So...mentioning

confidence: 99%

“…Recently, a successful demonstration of an opaque ultrathin single quantum well (SQW) solar cell based on a‐Si:H (barrier)/a‐Ge:H (QW) heterostructures embedded as a subwavelength nanophotonic resonator was reported 24,25 . Such concept allows a beneficial synergy between photonic and quantum confinements and a significant thickness‐dependent tuning of all the photovoltaic characteristics 24,26 . On the one hand, thin SQW (~20 nm) with narrow bandgap (Eg ~ 1 eV) yields high short circuit current (Jsc) but suffers from low open‐circuit voltage (Voc) and fill factor (FF).…”

Section: Introductionmentioning

confidence: 99%

Novel semi‐transparent solar cell based on ultrathin multiple Si/Ge quantum wells

Meddeb

Götz‐Köhler

Flathmann

et al. 2022

Progress in Photovoltaics

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Unlike conventional opaque solar cells, semi-transparent solar cells enable simultaneous electricity generation and light transmission. Along with solar energy harvesting, the offered multiple functionalities of these technologies, such as aesthetic appearance, visual comfort and thermal management, open diverse integration opportunities into versatile technological applications. In this work, the first demonstration of a novel semi-transparent solar cell based on ultrathin hydrogenated amorphous Si/Ge multiple quantum wells (MQW) is reported. Through optoelectronic modelling, the advantages of ultrathin MQW as photoactive material to overcome the intrinsic limitations of thin (20 nm) and ultrathin (2.5 nm) single quantum well (SQW) counterparts are explained. This allows extra degree of freedom for both optical design and bandgap engineering. Mainly, the multiplication of the QWs number in a periodic configuration, taking advantage of effective synergy between electronic and photonic confinements, leads to an improvement of photocurrent, while preserving high voltage and fill factor and ensuring significant transparency. The MQW new concept yields a boost in power conversion efficiency up to 3.4% and a considerable average visible transmission of about 33%. A light utilization efficiency above 1.1% is achieved, which can be considered as one of the highest among inorganic semitransparent solar cell technologies. The successful demonstration of ultrathin semitransparent Si/Ge MQW solar cells indicates the promising integration potential of this emerging photovoltaic technology for supplying systems in relevant applications such as in buildings, vehicles and greenhouses.

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Optical design and bandgap engineering in ultrathin multiple quantum well solar cell featuring photonic nanocavity

Meddeb,

Gehrke,

Vehse

2024

Progress in Photovoltaics

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Ultrathin solar cells are efficient and captivating devices with unique technological and scientific features in terms of minimal material consumption, fast fabrication processes, and good compatibility with semi‐transparent applications. Such photovoltaic (PV) technologies can enable effective synergy between optical and electronic confinements with large tuning capabilities of all the optoelectronic characteristics. In this work, the implications of the optical design and the bandgap engineering in ultrathin hydrogenated amorphous Si/Ge multiple quantum well (MQW) solar cells featuring photonic nanocavity are analyzed based on experimental measurements and optoelectronic modelling. By changing the period thicknesses and the positions of QWs inside the deep‐subwavelength nanophotonic resonator, the spatial and spectral distributions of the optical field and the local absorption are strongly affected. This leads to a modulation of the absorption resonance condition, the absorption edge and the resulting photocurrent outputs. Because of quantum confinement effect, the change of MQW configurations with different individual QW periods while keeping similar total thickness of about 20 nm alters both the bandgap energy and the band offset at the QW/barrier heterojunctions. This in turn controls the photovoltage as well as the carrier collection efficiency in solar cells. The highest open circuit voltage and fill factor values are achieved by employing MQW device configuration with 2.5 nm‐thin QWs. A record efficiency above 5.5% is reached for such emerging ultrathin Si/Ge MQW solar cell technology using thinner QWs with sufficient number, because of the optimum trade‐off between all the optoelectronic characteristic outputs. The presented design rules for opaque ultrathin solar cells with quantum‐confined nanostructures integrated in a photonic nanocavity can be generalized for the engineering of relevant multifunctional semitransparent PV devices.

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Investigation of Quantum Size Effects on the Optical Absorption in Ultrathin Single Quantum Well Solar Cell Embedded as a Nanophotonic Resonator

Cited by 5 publications

References 62 publications

Tunable Photovoltaics: Adapting Solar Cell Technologies to Versatile Applications

Tunable Photovoltaics: Adapting Solar Cell Technologies to Versatile Applications

Novel semi‐transparent solar cell based on ultrathin multiple Si/Ge quantum wells

Optical design and bandgap engineering in ultrathin multiple quantum well solar cell featuring photonic nanocavity

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