Fabrication of silicon nanowire based solar cells using TiO2/Al2O3 stack thin films

MRS Advances ◽  
2018 ◽  
Vol 3 (25) ◽  
pp. 1419-1426 ◽  
Author(s):  
Yasuyoshi Kurokawa ◽  
Ryota Nezasa ◽  
Shinya Kato ◽  
Hisashi Miyazaki ◽  
Isao Takahashi ◽  
...  
Keyword(s):  
Solar Cells ◽  
Surface Passivation ◽  
Silicon Nanowire ◽  
Surface Recombination ◽  
Single Layer ◽  
Minority Carrier Lifetime ◽  
Atomic Layer ◽  
Open Circuit ◽  
Surface Reflectance ◽  
Surface Recombination Rate

ABSTRACTTo improve conversion efficiency of silicon nanowire (SiNW) solar cells, it is very important to reduce the surface recombination rate on the surface of SiNWs, since SiNWs have a large surface area. We tried to cover SiNWs with aluminum oxide (Al2O3) and titanium oxide (TiO2) by atomic layer deposition (ALD), since Al2O3 grown by ALD provides an excellent level of surface passivation on silicon wafers and TiO2 has a higher refractive index than Al2O3, leading to the reduction of surface reflectance. The effective minority carrier lifetime in SiNW arrays embedded in a TiO2/Al2O3 stack layer of 94 μsec was obtained, which was comparable to an Al2O3 single layer. The surface reflectance of SiNW solar cells was drastically decreased below around 5% in all of the wavelength range using the Al2O3/TiO2/Al2O3 stack layer. Heterojunction SiNW solar cells with the structure of ITO/p-type hydrogenated amorphous silicon (a-Si:H)/n-type SiNWs embedded in Al2O3 and TiO2 stack layer for passivation/n-type a-Si:H/back electrode was fabricated, and a typical rectifying property and open-circuit voltage of 356 mV were successfully obtained.

Influence of Surface Recombination on the Performance of SiNW Solar Cells and the Preparation of a Passivation Film

2013 ◽  
Vol 1512 ◽  
Author(s):  
Shinya Kato ◽  
Yuya Watanabe ◽  
Yasuyoshi Kurokawa ◽  
Akira Yamada ◽  
Yoshimi Ohta ◽  
...  
Keyword(s):  
Solar Cells ◽  
Silicon Nanowire ◽  
Surface Recombination ◽  
Device Simulation ◽  
Minority Carrier Lifetime ◽  
Atomic Layer ◽  
Open Circuit ◽  
Surface Recombination Velocity ◽  
Passivation Film ◽  
Recombination Velocity

ABSTRACTAl2O3 was deposited on silicon nanowire (SiNW) arrays by atomic layer deposition (ALD) as a passivation layer to reduce surface recombination velocity. As a result, effective minority carrier lifetime was improved from 1.82 to 26.2 μs. From this result, the relative low-surface recombination rate of 2.73 cm/s was obtained from a calculation using one-dimensional device simulation (PC1D). The performance of SiNW solar cells was also simulated by considering the surface recombination velocity on the side of SiNWs using two-dimensional device simulation. It was found that Al2O3 deposited by ALD can improve open-circuit voltage of SiNW solar cells even if the structure has a high-aspect ratio and large surface area. Therefore, improvement in the performance of SiNW solar cells can be expected.

scholarly journals Study on Annealing Process of Aluminum Oxide Passivation Layer for PERC Solar Cells

Coatings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1052
Author(s):  
Yu-Chun Huang ◽  
Ricky Wenkuei Chuang
Keyword(s):  
Carrier Lifetime ◽  
Defect Density ◽  
Surface Recombination ◽  
Chemical Vapor ◽  
Minority Carrier Lifetime ◽  
Atomic Layer ◽  
Film Structure ◽  
Open Circuit ◽  
Annealing Process ◽  
Surface Recombination Velocity

In this study, Atomic Layer Deposition (ALD) equipment was used to deposit Al2O3 film on a p-type silicon wafer, trimethylaluminum (TMA) and H2O were used as precursor materials, and then the post-annealing process was conducted under atmospheric pressure. The Al2O3 films annealed at different temperatures between 200–500 °C were compared to ascertain the effect of passivation films and to confirm the changes in film structure and thickness before and after annealing through TEM images. Furthermore, the negative fixed charge and interface defect density were analyzed using the C-V measurement method. Photo-induced carrier generation was used to measure the effective minority carrier lifetime, the implied open-circuit voltage, and the effective surface recombination velocity of the film. The carrier lifetime was found to be the longest (2181.7 μs) for Al2O3/Si post-annealed at 400 °C. Finally, with the use of VHF (40.68 MHz) plasma-enhanced chemical vapor deposition (PECVD) equipment, a silicon nitride (SiNx) film was plated as an anti-reflection layer over the front side of the wafer and as a capping layer on the back to realize a passivated emitter and rear contact (PERC) solar cell with optimal efficiency up to 21.54%.

Diagnostics of Recombination Rate Homogeneity in Structures of Large-Area Solar Cells

2004 ◽  
Vol 97-98 ◽  
pp. 139-144
Author(s):  
Vitezslav Benda
Keyword(s):  
Solar Cells ◽  
Recombination Rate ◽  
Monochromatic Light ◽  
Surface Recombination ◽  
Antireflection Coating ◽  
Open Circuit ◽  
Large Area ◽  
Surface Recombination Rate ◽  
Local Defects ◽  
Efficiency And Reliability

The paper refers about a possibility to check recombination rate distribution over the area of power (large-area) solar cells from measured values of open circuit voltage VOC using local irradiation by monochromatic light of different wavelengths (LBIV . Light Beam Initiated Voltage). The method can give information both about recombination centres distribution in large-area solar cells and surface recombination rate at the antireflection coating. From VOC distribution, also position and extent of local defects can also be determined. The method can be used to investigate the influence of technology on characteristics of solar cells as an in-process checking with the aim of increasing efficiency and reliability of solar cells.

scholarly journals Etch Characteristics and Morphology of Al2O3/TiO2 Stacks for Silicon Surface Passivation

2019 ◽  
Vol 11 (14) ◽  
pp. 3857 ◽  
Author(s):  
Dongchul Suh
Keyword(s):  
Solar Cells ◽  
High Efficiency ◽  
Surface Passivation ◽  
Surface Texturing ◽  
Surface Recombination ◽  
Open Circuit ◽  
High Rate ◽  
Tio2 Films ◽  
Etch Pits ◽  
The Impact

Chemical processes are very important for the development of high-efficiency crystalline solar cells, mainly for surface texturing to improve light absorption and cleaning processes to reduce surface recombination. Recently, research has been focusing on the impact of chemical polishing on the performance of a passivated emitter and rear cells (PERC), with particular emphasis on the dielectric passivation layers on the front side. This study examined the influence of etching on the passivation of Al2O3/TiO2 stacks, where the films may each be deposited using a range of deposition and post-annealing parameters. Most TiO2 films deposited at 300 °C were resistant to chemical etching, and higher temperature deposition and annealing produced more chemical-resistant films. TiO2 films deposited at 100 °C were etched slightly by SC1 and SC2 solutions at room temperature, whereas they were etched at a relatively high rate in an HF solution, even when capped with a thick TiO2 layer (up to 50 nm in thickness); blistering occurred in 20-nm-thick Al2O3 films. In contrast to the as-deposited films, the annealed films showed a lower level of passivation as 1% HF etching proceeded. The implied open circuit voltage of the samples annealed at 300 °C after HF etching decreased more than those annealed at 400 °C. The dark area in the photoluminescence images was not resistant to the HF solution and showed more etch pits. The etching strategies developed in this study are expected to help setup integration processes and increase the applicability of this stack to solar cells.

scholarly journals Simulated Study and Surface Passivation of Lithium Fluoride-Based Electron Contact for High-Efficiency Silicon Heterojunction Solar Cells

2021 ◽  
Author(s):  
Muhammad Quddammah Khokhar ◽  
Shahzad Qamar Hussain ◽  
Sanchari Chowdhury ◽  
Muhammad Aleem Zahid ◽  
Pham Duy Phong ◽  
...  
Keyword(s):  
Solar Cells ◽  
Lithium Fluoride ◽  
High Efficiency ◽  
Surface Passivation ◽  
Minority Carrier Lifetime ◽  
Open Circuit ◽  
Passivation Layer ◽  
Heterojunction Solar Cells ◽  
Electron Extraction ◽  
Silicon Heterojunction Solar Cells

Abstract Numerical simulation and experimental techniques were used to investigate lithium fluoride (LiFx) films as an electron extraction layer for the application of silicon heterojunction (SHJ) solar cells, with a focus on the paths toward excellent surface passivation and superior efficiency. The presence of a 7 nm thick hydrogenated intrinsic amorphous silicon (a-Si:H(i)) passivation layer along with thermally evaporated 4 nm thick LiFx resulted in outstanding passivation properties and suppresses the recombination of carriers. As a result, minority carrier lifetime (τeff) as well as implied open-circuit voltage (iVoc) reached up 933 μs and iVoc of 734 mV, accordingly at 120°C annealing temperature. A detailed simulated study was performed for the complete LiFx based SHJ solar cells to achieve superior efficiency. Optimized performance of SHJ solar cells using a LiFx layer thickness of 4 nm with energy bandgap (Eg) of 10.9 eV and the work function of 3.9 eV was shown as: Voc=745.7 mV, Jsc=38.21 mA/cm2, FF=82.17%, and =23.41%. Generally, our work offers an improved understanding of the passivation layer, electron extraction layer, and their combined effects on SHJ solar cells via simulation.

scholarly journals Enhanced Performance of Nanotextured Silicon Solar Cells with Excellent Light-Trapping Properties

Photonics ◽  
2021 ◽  
Vol 8 (7) ◽  
pp. 272
Author(s):  
Bingfei Dou ◽  
Rui Jia ◽  
Zhao Xing ◽  
Xiaojiang Yao ◽  
Dongping Xiao ◽  
...  
Keyword(s):  
Solar Cells ◽  
Light Trapping ◽  
Short Circuit ◽  
Surface Recombination ◽  
Atomic Layer ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Surface Recombination Velocity ◽  
Electrode Contact ◽  
Recombination Velocity

Light-trapping nanostructures have been widely used for improving solar cells’ performance, but the higher surface recombination and poor electrode contact introduced need to be addressed. In this work, silicon nanostructures were synthesized via silver-catalyzed etching to texturize solar cells. Atomic-layer-deposited Al2O3 passivated the nanotextured cells. A surface recombination velocity of 126 cm/s was obtained, much lower than the 228 cm/s of the SiNX-passivated one. Additionally, the open-circuit voltage (VOC) of the nanotextured cells improved significantly from 582 to 610 mV, as did the short-circuit current (JSC) from 25.5 to 31 mA/cm2. Furthermore, the electrode contact property was enhanced by light-induced plating. A best efficiency of 13.3% for nano-textured cells was obtained, which is higher than the planar cell’s 12%.

Spray deposited TiO2 thin films for large-area TiO2/p-Si heterojunction solar cells

2021 ◽  
Author(s):  
Manas R. Samantaray ◽  
Prashant Kumar Gautam ◽  
Dhriti Sundar Ghosh ◽  
Nikhil Chander
Keyword(s):  
Solar Cells ◽  
Surface Passivation ◽  
Spray Deposition ◽  
Minority Carrier Lifetime ◽  
Open Circuit ◽  
Deposition Technique ◽  
Large Area ◽  
Tio2 Thin Films ◽  
Heterojunction Solar Cells ◽  
Si Substrates

Abstract Carrier selective contacts (CSC) have the potential to lower the cost of photovoltaic (PV) cells. In the present work p-Si/TiO2 heterojunction solar cells have been fabricated using titanium dioxide (TiO2) as an electron-selective layer. Thin uniform anatase TiO2 films have been deposited using a commercially viable spray deposition technique over large area Si substrates. With a simple architecture of Al (200 nm fingers)/Al (15 nm thin film)/TiO2/c-Si(p)/Ag (200 nm), a highest conversion efficiency of 1.56 % has been achieved for the TiO2 carrier selective contact based solar cell with an active area of ~3.84 cm2. The minority carrier lifetime value of the TiO2 coated Si wafer was found to be less than that of the uncoated wafer, indicating the inability of the anatase TiO2 layer to provide surface passivation. Suns-VOC measurements yielded comparable values of the implied open circuit voltage for both the uncoated and the TiO2 coated Si wafers. Spray deposition technique can be used for scalable fabrication of carrier selective contact based heterojunction solar cells.

scholarly journals Surface Passivation and Antireflection Behavior of ALD on n-Type Silicon for Solar Cells

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Ing-Song Yu ◽  
Yu-Wun Wang ◽  
Hsyi-En Cheng ◽  
Zu-Po Yang ◽  
Chun-Tin Lin
Keyword(s):  
Thin Films ◽  
Solar Cells ◽  
Surface Passivation ◽  
Weighted Average ◽  
Minority Carrier Lifetime ◽  
Atomic Layer ◽  
Antireflection Coating ◽  
Kelvin Probe ◽  
Type Silicon ◽  
Deposition Parameters

Atomic layer deposition, a method of excellent step coverage and conformal deposition, was used to deposit TiO2thin films for the surface passivation and antireflection coating of silicon solar cells. TiO2thin films deposited at different temperatures (200°C, 300°C, 400°C, and 500°C) on FZ n-type silicon wafers are in the thickness of 66.4 nm ± 1.1 nm and in the form of self-limiting growth. For the properties of surface passivation, Si surface is effectively passivated by the 200°C deposition TiO2thin film. Its effective minority carrier lifetime, measured by the photoconductance decay method, is improved 133% at the injection level of  cm−3. Depending on different deposition parameters and annealing processes, we can control the crystallinity of TiO2and find low-temperature TiO2phase (anatase) better passivation performance than the high-temperature one (rutile), which is consistent with the results of work function measured by Kelvin probe. In addition, TiO2thin films on polished Si wafer serve as good ARC layers with refractive index between 2.13 and 2.44 at 632.8 nm. Weighted average reflectance at AM1.5G reduces more than half after the deposition of TiO2. Finally, surface passivation and antireflection properties of TiO2are stable after the cofire process of conventional crystalline Si solar cells.

scholarly journals Numerical Simulation Analysis of Ag Crystallite Effects on Interface of Front Metal and Silicon in the PERC Solar Cell

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 592
Author(s):  
Myeong Sang Jeong ◽  
Yonghwan Lee ◽  
Ka-Hyun Kim ◽  
Sungjin Choi ◽  
Min Gu Kang ◽  
...  
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
High Efficiency ◽  
Open Circuit Voltage ◽  
Surface Recombination ◽  
Open Circuit ◽  
Surface Recombination Velocity ◽  
Metal Interface ◽  
Ag Crystallites ◽  
Recombination Velocity

In the fabrication of crystalline silicon solar cells, the contact properties between the front metal electrode and silicon are one of the most important parameters for achieving high-efficiency, as it is an integral element in the formation of solar cell electrodes. This entails an increase in the surface recombination velocity and a drop in the open-circuit voltage of the solar cell; hence, controlling the recombination velocity at the metal-silicon interface becomes a critical factor in the process. In this study, the distribution of Ag crystallites formed on the silicon-metal interface, the surface recombination velocity in the silicon-metal interface and the resulting changes in the performance of the Passivated Emitter and Rear Contact (PERC) solar cells were analyzed by controlling the firing temperature. The Ag crystallite distribution gradually increased corresponding to a firing temperature increase from 850 ∘C to 950 ∘C. The surface recombination velocity at the silicon-metal interface increased from 353 to 599 cm/s and the open-circuit voltage of the PERC solar cell decreased from 659.7 to 647 mV. Technology Computer-Aided Design (TCAD) simulation was used for detailed analysis on the effect of the surface recombination velocity at the silicon-metal interface on the PERC solar cell performance. Simulations showed that the increase in the distribution of Ag crystallites and surface recombination velocity at the silicon-metal interface played an important role in the decrease of open-circuit voltage of the PERC solar cell at temperatures of 850–900 ∘C, whereas the damage caused by the emitter over fire was determined as the main cause of the voltage drop at 950 ∘C. These results are expected to serve as a steppingstone for further research on improvement in the silicon-metal interface properties of silicon-based solar cells and investigation on high-efficiency solar cells.

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