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SUMMARY:46th IEEE Photovoltaic Specialists Conference (Chicago)
DTSTART;VALUE=DATE:20190616
DTSTAMP:20260428T111346Z
UID:f8a80568e70b01e25e0b55c896c28da3c586d9089e962ecbd52bb46d
CATEGORIES:Conferences - Seminars
DESCRIPTION:Jan Hascke\, Angela Fioretti\nJan Hascke\, Angela Fioretti and
  Mathieu Boccard will be in Chicago from 16 to 21 of June 2019 to present 
 their excellent results. Jan will present his work on the role of lateral 
 transport of minority carrier. His talk his entitled "Injection-dependent 
 lateral resistance in front-junction solar cells with nc-Si:H and a-Si:H h
 ole selective contact".\nAngela will advertise an advanced low temperature
  deposition method for enhanced cristalinity of thin p-type mc-Si:H contac
 t layers. Finally\, Mathieu will present how to reach high current densiti
 es in high-efficiency silicon heterojunction solar cells.\n\nAbstract J. H
 ascke\nWe investigate the role of lateral transport of minority carriers i
 n the wafer for front-junction solar cells. The study is based on two sili
 con heterojunction solar cells with p-type amorphous (a-Si)\, and nanocrys
 talline (nc-Si) silicon as hole selective layer respectively. The solar ce
 lls feature similar certified efficiencies (23.23% and 23.45%). Unexpected
 ly\, FF and RS at MPP of both solar cells are also similar. Fitting the JV
  curves in high-forward bias\, and analytical calculations suggest that la
 teral transport is also taking place in the wafer at high injection\, desp
 ite the front–junction configuration. The calculations reveal that junct
 ion-related RS is lower with nc-Si(p) than with a-Si(p). The results under
 line the importance of analyzing JV curves over a wide voltage range to un
 ravel different phenomena determining FF.\n\n\nAbstract A. Fioretti:\nHete
 rojunction-based silicon solar cells have reached record-breaking efficien
 cy\, particularly when implemented in all-back-contacted architectures. Cl
 assical\, two-side contacted silicon heterojunction (SHJ) solar cells suff
 er from parasitic absorption and series resistance losses in the amorphous
  silicon contacts. An alternative to doped amorphous silicon is to use dop
 ed microcrystalline silicon instead\, which exhibits improved transparency
  and charge extraction while still providing the superior passivation qual
 ity of all-silicon contact stacks. However\, depositing films with high cr
 ystalline volume fraction thin enough to maintain improved transparency ha
 s remained a challenge until recently. In this work\, we combine the succe
 ssful pretreatment method of previous studies with lower deposition temper
 ature to achieve enhanced crystallinity in thin p-type mc-Si:H contact lay
 ers. With these layers\, we demonstrate Jsc gains of 1 mA/cm2\, while red
 ucing series resistance to 1 ohm cm2\, leading to cells with certified h
 =23.5%. Raman spectroscopy determined that deposition temperature below 20
 0 °C leads to an increase in crystalline volume fraction from 35% to 55% 
 for p-type films\, whereas n-type film crystallinity remains constant. Ext
 ernal quantum efficiency measurements revealed that enhanced p-layer cryst
 allinity results in short wavelength efficiency gains\, consistent with re
 duced parasitic absorption. Additionally\, ellipsometry of representative 
 p-type mc-Si:H deposited at varying temperature showed that E04 shifts to 
 higher energy for lower temperature layers\, suggesting a widening bandgap
 . Dark conductivity measurements showed that despite the increase in cryst
 allinity\, both activation energy and conductivity are similar among all f
 ilms\, no matter the deposition temperature. Using PC1D illuminated band d
 iagrams\, we explain these results as due to increased band bending at the
  c-Si interface with the p-type contact\, which is a direct result of the 
 wider bandgap for higher crystallinity\, low-temperature layers. These fin
 dings provide a method to improve SHJ solar cells performance\, while offe
 ring insight into the importance of band bending considerations when optim
 izing heterojunction designs.\n\n\n 
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STATUS:CONFIRMED
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