Investigation on limiting factors affecting Cu2ZnGeSe4 efficiency: Effect of annealing conditions and surface treatment

Combinatorial and machine learning approaches for the analysis of Cu2ZnGeSe4: influence of the off-stoichiometry on defect formation and solar cell performance

“…In addition, it is hard to envision how the formation of the ZnSe phase could inuence Cu/Zn disordering in the CZGSe compound. On the other hand, even taking into account the optimal temperature treatment for the formation of good crystalline quality CZGSe phase, 16,29 the presence of ZnSe grains can greatly inuence the formation and size of the kesterite grains, 30 leading to a worsening of its crystalline quality and grain size, and causing the appearance of phonon connement in agreement to the observed red shi and broadening of the kesterite Raman peaks. In addition to the ZnSe phase, the blue excitation wavelength is also sensitive to the GeSe 2 phase.…”

“…This is in agreement with previously published values for high efficiency solar cells based on CZGSe. 16,17,29 Furthermore, the efficiency of the devices seems to be less dependent on the [Cu]/ ([Zn] + [Sn]) ratio, as long as the Cu-poor condition is respected (e.g. similar efficiencies were obtained for [Cu]/([Zn] + [Sn]) ¼ 0.67 in ref.…”

Emerging Chalcogenide Thin Films for Solar Energy Harvesting Devices

“…67 Another study reported a large increase in V OC from 368 to 582 mV upon surface treatment with KCN. 337 Modification of CdS deposition parameters was also explored, and a high PCE of 7.6% was obtained. 312 Attempts to replace CdS with another buffer layer having a better band alignment with Cu 2 ZnGeSe 4 led to a high V OC of 730 mV, compared to 617 mV using CdS.…”

“…The record 8.5% PCE was indeed achieved via surface etching treatment and post-CdS-deposition annealing . Another study reported a large increase in V OC from 368 to 582 mV upon surface treatment with KCN . Modification of CdS deposition parameters was also explored, and a high PCE of 7.6% was obtained .…”

Rear Band gap Grading Strategies on Sn–Ge-Alloyed Kesterite Solar Cells

“…Last but not least, a promising strategy for cationic band gap engineering lies in the partial substitution of Sn by Ge in the Cu 2 Zn­(Sn,Ge)­(S,Se) 4 (CZTGSe) lattice, which does not modify the kesterite structure. Additionally, Ge alloying can potentially promote grain growth and suppress the formation of Sn-related defects. − Furthermore, Ge is similar to the isoelectronic Sn atom but with a lower atomic number, hence making it possible to tune the electronic band profile through modifications of the IV–VI sp-orbital anti-bonding of the conduction band edge. , Additionally, deep Sn-related defects which are responsible for electron trapping in kesterite are mainly related to Sn 2+ and Sn 4+ multivalence, and the possibility to form intermediate Sn 3+ oxidation state, that has been proposed at the origin of killer defects on kesterite . In this sense, the formation of deep defects related to multivalence can be in principle reduced by substituting Sn with Ge because it is well known that +4 state is more likely to occur with Ge than with Sn, reducing the probability of creating detrimental lower oxidation states.…”