Suns-photoluminescence: Contactless determination of current-voltage characteristics of silicon wafers

Abstract

In good silicon solar cells, the separation of the quasi-Fermi energies Δη in the bulk is equivalent to the cell voltage. Photoluminescence is used to measure Δη in both bifacial solar cells and partly processed solar cells. The bifacial cells are used to demonstrate that simultaneous measurement of the photoluminescence signal and of the variable incident light intensity yields pseudo current-voltage characteristics, equivalent to Suns-open circuit voltage (VOC) measurements, but in contactless mode. The applicability of this method to unfinished solar cells, without the need for a solar cell structure, is demonstrated on silicon wafers after various processing steps.

Photoluminescence and time‐resolved photoluminescence in Cu(In,Ga)Se2 thin films and solar cells

“…PL in the CIGS solar cell is much different from that in the CIGS film and CdS/CIGS, and thus, care should be taken for the measurements and the analysis of PL in the CIGS solar cell. In silicon solar cells, PL has been developed as a contactless method for the determination of the current-voltage characteristics [12,13]. In CuGaSe 2 solar cells, dc-bias voltage dependence of PL and electromodulated PL have been analyzed in detail [14].…”

Lock-in and Heterodyne Carrierographic Imaging Characterization of Industrial Multicrystalline Silicon Solar Cells

“…The dependence of the surface-integrated LICG amplitude on the terminal photovoltage exhibits an exponential behavior under 10 Hz laser illumination. This is broadly explained by the fact that under dc conditions the photovoltage is related to the excess minority carrier in the form [15], where η is the separation of quasi-Fermi energies, N D is the doping concentration, n is the excess minority carrier concentration, and I PL is dc PL intensity. Here η is assumed constant along the base width.…”

Investigation of edge recombination effects in silicon solar cell structures using photoluminescence

“…[1][2][3][4] Here we use characterization techniques based on quasi-steady-state photoluminescence ͑QSS-PL͒, specifically spatially averaged injection level dependent photoluminescence lifetime measurements, Suns-photoluminescence ͑Suns-PL͒ and photoluminescence imaging which have recently been described. [5][6][7][8] Similar to photoconductance and infrared free carrier absorption, PL is contactless and can be used for partially finished devices. However, unlike these methods QSS-PL is able to measure the minority carrier lifetime to very low injection levels ͑10 10 -10 11 cm −3 ͒ without the influence of artifacts such as depletion region modulation 9 and trapping.…”

“…The minority carrier densities were then converted into implied voltages yielding Suns-PL curves. 7 Finally, the normalized gradient was calculated at each point on this curve to yield a local ideality factor versus voltage curve, a technique that has been shown to be useful for interpreting recombination mechanisms. 11 All measurements were made on a 2 ϫ 2 cm 2 active area in the center of the samples; on the relevant sample, this area was completely within the isolation trench.…”