Rear Surface Optimization of CZTS Solar Cells by Use of a Passivation Layer With Nanosized Point Openings

Abstract

Previously, an innovative way to reduce rear interface recombination in Cu(In,Ga)(S,Se) 2 (CIGSSe) solar cells has been successfully developed. In this work, this concept is established in Cu 2 (Zn,Sn)(S,Se) 4 (CZTSSe) cells to demonstrate its potential for other thin-film technologies. Therefore, ultrathin CZTS cells with an Al 2 O 3 rear surface passivation layer having nanosized point openings are fabricated. The results indicate that introducing such a passivation layer can have a positive impact on open-circuit voltage (V O C ; +17%rel.), short-circuit current (J S C ; +5%rel.), and fill factor (FF; +9%rel.), compared with corresponding unpassivated cells. Hence, a promising efficiency improvement of 32%rel. is obtained for the rear passivated cells.

Improvement of kesterite solar cell performance by solution synthesized MoO3 interfacial layer

“…This might be due to the reduction of the decomposition reactions at the rear interface by introducing MoO 3 layer and improving the rear surface quality. Several studies have already reported the instability of Mo during the selenization/sulfurization process that leads to the formation of voids, and secondary phases and introduce defects such as Se vacancies . Another hypothesis could be the role of oxygen in passivation of defects, as in high temperature processing the oxygen can be released and fill the different vacancies.…”

Passivation of Interfaces in Thin Film Solar Cells: Understanding the Effects of a Nanostructured Rear Point Contact Layer

“…[15][16][17][18] Such passivation layer can lead to three advantageous effects: (i) chemical passivation; (ii) field effect passivation; (iii) increased reflection at the rear contact; all while maintaining good electrical contact and devices with high values of fill factor. [15][16][17][18] Such passivation layer can lead to three advantageous effects: (i) chemical passivation; (ii) field effect passivation; (iii) increased reflection at the rear contact; all while maintaining good electrical contact and devices with high values of fill factor.…”

“…It has been demonstrated that the rear interface can be effectively passivated by an Al 2 O 3 nanopatterned layer forming a point contact structure. [15][16][17][18] Such passivation layer can lead to three advantageous effects: (i) chemical passivation; (ii) field effect passivation; (iii) increased reflection at the rear contact; all while maintaining good electrical contact and devices with high values of fill factor. Chemical passivation, a terminology coming from the silicon technology, is simply related with a reduction on the interface defect density and it is still an electronic effect.…”

Optical Lithography Patterning of SiO2 Layers for Interface Passivation of Thin Film Solar Cells

“…Afterwards, a physical etching process is performed through the dielectric exposing Mo, allowing for contact of the rear electrode to the CIGS. For this purpose, a reactive ion etching (RIE) process on SPTS ICP is used which according to our experience, does not change the contact properties of the Mo with CIGS . The system is capable of etching deep sub‐micron features with near vertical sidewalls (anisotropic) and provides good selectivity.…”