Revani diffusion model in Cu(In,Ga)Se<sub>2</sub>

Colombara, Diego; Stanbery, Billy J.; Sozzi, Giovanna

doi:10.1039/d3ta03690a

Cited by 5 publications

(2 citation statements)

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“…For the effect of Na several mechanisms have been proposed: One mechanism suggests that Na increases the density of copper (Cu) vacancies, which act as acceptors, thereby enhancing doping due to the higher number of acceptors [61]. Another mechanism proposes that Na decreases the In Cu antisite donors [6,60,62]. Recent studies suggest that Na facilitates the migration of In Cu antisites from the grain interior to GBs, thereby reduces the compensation within the grains and increases the doping level [62].…”

Section: Electrostatic Potential Fluctuations and Intensity Dependent...mentioning

confidence: 99%

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Grain boundaries are not the source of Urbach tails in Cu(In,Ga)Se₂ absorbers

Gharabeiki,

Farooq,

Wang

et al. 2024

J. Phys. Energy

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The presence of Urbach tails in Cu(In,Ga)Se2 (CIGSe) absorbers has been identified as a limiting factor for the performance of the CIGSe solar cells. The tail states contribute to both radiative and non-radiative recombination processes, ultimately leading to a reduction in the open-circuit voltage (VOC) and, consequently, decreasing the overall efficiency of CIGSe devices. Urbach tails result from structural and thermal disorders. The Urbach tails can be characterized by the Urbach energy, which is associated with the magnitude of the tail states. Within polycrystalline CIGSe absorbers, grain boundaries can be considered as structural disorder and, therefore, can potentially contribute to the Urbach tails. In fact, it has been proposed that the band bending at grain boundaries contribute significantly to the tail states. This study focuses on examining the correlation between Urbach tails and the band bending at the grain boundaries. The Urbach energies of the CIGSe samples are extracted from photoluminescence (PL) measurements, which reveal that the introduction of Sodium (Na) into the material can lead to a reduction in the Urbach energy, and an even further decrease can be achieved through the RbF post-deposition treatment (PDT). The band bending at the grain boundaries is investigated by Kelvin probe force microscopy (KPFM) measurements. A thorough statistical analysis of more than 340 grain boundaries does not show any correlation between Urbach tails and grain boundaries. We measure small band bending values at the grain boundaries, in the range of the thermal energy (26meV at room temperature). Furthermore, our intensity dependent PL measurements indicate that Urbach tails are, at least in part, a result of electrostatic potential fluctuations. This supports the model that the introduction of alkali elements mainly decreases the magnitude of electrostatic potential fluctuations, resulting in a subsequent reduction in the Urbach energy.

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Section: Electrostatic Potential Fluctuations and Intensity Dependent...mentioning

confidence: 99%

“…Another mechanism proposes that Na decreases the In Cu antisite donors [6,60,62]. Recent studies suggest that Na facilitates the migration of In Cu antisites from the grain interior to GBs, thereby reduces the compensation within the grains and increases the doping level [62].…”

Section: Electrostatic Potential Fluctuations and Intensity Dependent...mentioning

confidence: 99%