Surface potential on grain boundaries and intragrains of highly efficient Cu2ZnSn(S,Se)4 thin-films grown by two-step sputtering process

A low-cost, sulfurization free approach to control optical and electronic properties of Cu2ZnSnS4 via precursor variation

“…Most commonly, KPFM has been used to correlate grain boundary potentials with film quality. KPFM done on reactively co-sputtered films of CZTS and CZTSSe clearly demonstrated that there exists a higher, positive surface potential at the grain boundaries and this finding was correlated with conducting AFM data showing a higher current in these same regions [26]; another study on CZTS films grown by the same method showed using conducting AFM and KPFM that the photocurrent primarily flowed along grain boundaries and capacitance microscopy [27] was used to show that the charge separation takes place at the interface of the grain boundary and grain and the current predominantly moved along these boundaries [28,29]. KPFM has also been used to detect the presence of unwanted secondary phases on the surface of CZTS films by KCN-etching [30] as well as in CZTSSe by depth profiling [31].…”

Band Gap Tuning of Cu2ZnGeSxSe4-x Absorbers for Thin-Film Solar Cells

“…The best carrier collection is achieved between 520 and 550 nm for all samples; in the longer wavelength region, the charge carrier collection is strictly declining. The reason might be the high number of grain boundaries that are suspected to act as recombination centers [25]. However, for CZTSSe, it was shown that larger grains do not necessarily improve the solar cell efficiency [26].…”

Optical and surface probe investigation of secondary phases in Cu 2 ZnSnS 4 films grown by electrochemical deposition

“…In previous studies, GBs in the CIGS [47][48][49] and CZTSSe thinfilms were observed to induce downward band bending, and thus the GBs act as efficient electron and hole carrier collection region [50][51][52]. Furthermore, our group reported that a high-efficiency CZTSSe thin-film exhibits a dominant positive potential for the GBs and a negative potential at the IGs, forming downward band bending.…”

“…This results in charge separation at the GBs, similar to the CIGS thin-films. Hence, electron and hole carriers are collected at some GBs, and, consequently, the current density (J SC ) and the shunt resistance are enhanced since there is a decrease in the electron-hole carrier recombination at the GBs [52].…”