minority carrier lifetime
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Author(s):  
Manas R. Samantaray ◽  
Prashant Kumar Gautam ◽  
Dhriti Sundar Ghosh ◽  
Nikhil Chander

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.


Author(s):  
Muhammad Quddammah Khokhar ◽  
Shahzad Qamar Hussain ◽  
Sanchari Chowdhury ◽  
Muhammad Aleem Zahid ◽  
Pham Duy Phong ◽  
...  

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.


2021 ◽  
Vol 119 (18) ◽  
pp. 182106
Author(s):  
K. Shima ◽  
R. Tanaka ◽  
S. Takashima ◽  
K. Ueno ◽  
M. Edo ◽  
...  

2021 ◽  
Author(s):  
Panbing Zhou ◽  
Shilong Liu ◽  
Naigen Zhou ◽  
Xiuqin Wei ◽  
Lang Zhou

Abstract Photoluminescence(PL)imaging techniques and the minority carrier lifetime test system were employed to investigate the variation of the interstitial iron (Fei) concentration, the recombination activity of structural defects and the minority carrier lifetime of cast multicrystalline silicon (mc-Si) in response to the cooling rate after heating. The results showed that when the mc-Si wafers are heated to high-temperature (1000 °C) and then cooled to ambient temperature with different cooling rate, the Fei concentration, the number of recombination active dislocations and grain boundaries increased as the cooling rate rises while the minority carrier lifetime decreased. If cast mc-Si is heated followed by faster cooling at 30 °C/s, the Fei concentration increase by 223% and the electrical activity of grain boundaries, dislocations and intragrain increase significantly, that is to say, the whole wafer is heavily contaminated with metal impurities, and present extremely low minority carrier lifetime.


Coatings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1052
Author(s):  
Yu-Chun Huang ◽  
Ricky Wenkuei Chuang

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%.


2021 ◽  
Vol 870 ◽  
pp. 159477
Author(s):  
Jing Wang ◽  
Xiaodan Wang ◽  
Jiafan Chen ◽  
Xiaodong Gao ◽  
Xionghui Zeng ◽  
...  

2021 ◽  
Vol 129 (18) ◽  
pp. 184501
Author(s):  
Rigo A. Carrasco ◽  
Christian P. Morath ◽  
Perry C. Grant ◽  
Gamini Ariyawansa ◽  
Chad A. Stephenson ◽  
...  

2021 ◽  
Vol 11 (8) ◽  
pp. 3527
Author(s):  
Jian Lin ◽  
Hongsub Jee ◽  
Jangwon Yoo ◽  
Junsin Yi ◽  
Chaehwan Jeong ◽  
...  

We report the effects of H2S passivation on the effective minority carrier lifetime of crystalline silicon (c-Si) wafers. c-Si wafers were thermally annealed under an H2S atmosphere at various temperatures. The initial minority carrier lifetime (6.97 μs) of a c-Si wafer without any passivation treatments was also measured for comparison. The highest minority carrier lifetime gain of 2030% was observed at an annealing temperature of 600 °C. The X-ray photoelectron spectroscopy analysis revealed that S atoms were bonded to Si atoms after H2S annealing treatment. This indicates that the increase in minority carrier lifetime originating from the effect of sulfur passivation on the silicon wafer surface involves dangling bonds.


2021 ◽  
Author(s):  
Aravindan Gurusamy ◽  
S. Sanmugavel ◽  
S. G. Nagarajan ◽  
V. Kesavan ◽  
M. Sriniv ◽  
...  

Abstract The boron doped multi-crystalline silicon (mc-Si) ingot was grown using the directional solidification process. Grown ingots were converted into bricks and then to wafers. We have fabricated silicon solar cells from the multi-crystalline silicon wafers. The minority carrier lifetime of the wafers is around 15-25 ms. Annealing was made after back and front contact during the fabrication process. The effect of back contact annealing temperature has been investigated. Annealing the device at 5830C for 5 sec gives better results. Typical open circuit voltage (Voc) of the devices is around ~540-550mV. The best cell had a power conversion efficiency of ~9 % with a typical acceptor doping density ~ 2.35 E+15 per cm3 (The devices reported here do not have AR coating layer, no passivation was done and the surfaces are also not textured).


2021 ◽  
Vol 93 (4) ◽  
pp. 40101
Author(s):  
Sarra Dehili ◽  
Damien Barakel ◽  
Laurent Ottaviani ◽  
Olivier Palais

In Silicon, impurities introduce recombination centers and degrade the minority carrier lifetime. It is therefore important to identify the nature of these impurities through their characteristics: the capture cross section σ and the defect level Et. For this purpose, a study of the bulk lifetime of minority carriers can be carried out. The temperature dependence of the lifetime based on the Shockley-Read-Hall (SRH) statistic and related to recombination through defects is studied. Nickel and gold in p-type Si have been selected for the SRH lifetime modeling. The objective of the analysis is to carry out a study to evaluate gold and nickel identification prior to temperature-dependent lifetime measurements using the microwave phase-shift (μW-PS) technique. The μW-PS is derived from the PCD technique and is sensitive to lower impurity concentrations. It has been shown that both gold and nickel can be unambiguously identified from the calculated TDLS curves.


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