Efficiency Enhancement of Kesterite Cu₂ZnSnS₄ Solar Cells via Solution-Processed Ultrathin Tin Oxide Intermediate Layer at Absorber/Buffer Interface

Abstract

The ultrathin SnO2 intermediate layer deposited by a successive ionic layer adsorption and reaction (SILAR) method was introduced into the heterointerface between p-type Cu2ZnSnS4 (CZTS) absorber and n-type CdS buffer for interface defect passivation in kesterite thin film solar cells. CZTS solar cells with SnO2 intermediate layers show higher open circuit voltage (V oc) of 657 mV and fill factor (FF) of 62.8%, compared to its counterpart cells without the SnO2 intermediate layer, which have V oc of 638 mV and FF of 52.4%, resulting in improvement in the overall efficiency from 6.82% to 8.47%. The mitigation of the V oc deficit and the improvement of FF are believed to result from the integrated effects of CZTS/CdS heterointerface passivation, shunt blocking, and band alignments. The passivation effect is further affirmed by the improved carrier lifetime. Furthermore, external quantum efficiency profiles show a strengthened blue optical response which is contributed by the decrease of CdS thickness. This work provides a new insight into the CdS/CZTS interface passivation, shunt blocking, and optimization of band alignments, based on solution-processed SnO2.

Passivation of CdS/Cu2ZnSnS4 Interface from Surface Treatments of Kesterite‐Based Thin‐Film Solar Cells

“…This is in agreement with previous reports on the efficiency enhancement of kesterite CZTS solar cells through SnO 2 interface passivation. [ 36 ]…”

“…This is in agreement with previous reports on the efficiency enhancement of kesterite CZTS solar cells through SnO 2 interface passivation. [36] 4. Conclusions XPS and HAXPES have been used to study the chemical and electronic properties of the absorber surface and buffer/absorber interface when a CZTS solar cell absorber was subjected to different surface treatments and subsequent CdS deposition.…”

Partial substitution of the CdS buffer layer with interplay of fullerenes in kesterite solar cells

“…In this case, the surface passivation of the absorber is of significant interest, as the interface between CZTS and CdS presents several issues due to the valence band offset and secondary phases which induces interface recombination. Usually, an etching treatment 31,32 or an oxide interlayer 33,34 is required for a passivation of interface defects. Figure 4 shows the J-V curves of the best device for each condition under AM1.5 illumination condition, and the average values are showed in the Table 2.…”

12.29% Low Temperature–Processed Dopant‐Free CdS/p‐Si Heterojunction Solar Cells

“…Cadmium sulfide (CdS) has a band gap near 2.4 eV and has been used extensively as window/buffer layer in various thin film solar cells based on CdTe, CuInGaSe 2 (CIGS), and Cu 2 ZnSn(S,Se) 4 (CZTSSe) . Without intentional doping, CdS is an n‐type semiconductor with a rather high photoconductivity.…”