Bifacial Cu₂ZnSn(S,Se)₄ Thin Film Solar Cell Based on Molecular Ink and Rapid Thermal Processing

Abstract

The use of transparent conducting oxides (TCO) as a back contact for Cu2ZnSn(S,Se)4 (CZTSSe) thin film solar cell enables light absorption from both front and rear sides and allows for the fabrication of semi‐transparent photovoltaic devices. However, the CZTSSe solar cell based on TCO substrate suffers from high parasitic losses owing to the long post‐annealing time at elevated temperature required for high‐quality absorber. This work aims to overcome this issue by carefully tailoring the annealing conditions to obtain high‐performance solar cell. Rapid thermal processing is used to instantaneously generate high Se vapor pressure at target temperature and shorten the annealing time. The crystalline quality, morphology, and particularly the photovoltaic performance of the resulting CZTSSe thin film are systematically investigated. It is found that the increase of annealing temperature and time improves the crystalline quality but unfortunately deteriorates the device performance owing to increasing parasitic losses. Increasing the amount of Se allows to get highly crystalline absorber within 7 min of annealing, yielding a total area 5.56% efficient CZTSSe solar cell with front illumination resulting from reducing parasitic losses. This work provides a simple approach to preserve the back contact without using a complex interfacial layer.

Solution-Deposited MoO3 Interface Layer for High-Performance Bifacial Kesterite Thin Film Solar Cell

“…For example, Lin and co-workers improved the crystalline quality of CZTSSe absorber layer and optimized CZTSSe/FTO interface by enhancing Se vapor pressure and decreasing selenization time, and achieved a PCE of 5.56%. 21 Moises et al enhanced the PCEs of bifacial CZTSSe devices from 3.1 to 7.7% through inserting a Na-doped Mo nanolayer between FTO electrode and CZTSSe absorber thin film. 20 Wang et al elevated the CZTSSe grain growth and charge transport kinetics using an Ag-doped strategy and TiO 2 as a buffer layer, and fabricated an ultrathin device with a PCE of 9.7%.…”

“…In recent years, more and more researchers have focused on fabricating CZTSSe solar cells on transparent and conductive substrates to substitute for the commonly used Mo back electrode. Transparent conductive oxides (TCOs), such as antimony-doped tin oxide (ATO), indium tin oxide (ITO) − and fluorine-doped tin oxide (FTO), − are considered as the replacement of opaque Mo, which have been used to fabricate semitransparent CZTSSe solar cells. − These bifacial CZTSSe solar cells as the building integrated photovoltaics can absorb and utilize light from the outside and inside buildings in the future. Among these different TCOs, FTO possesses the advantages of higher thermal stability and abundant earth composition. , Therefore, FTO substrates are usually used as the back electrode to replace the traditional Mo electrode for fabricated bifacial CZTSSe solar cells.…”

Semitransparent Wide Bandgap Cu2ZnGe(S,Se)4 Thin‐Film Solar Cells: Role of the Sulfurization Process

“…It is interesting to note that there are not so many works about kesterite solar cells on transparent electrodes. [16][17][18][19][20][21][22][23][24] Tin-doped indium oxide, In 2 O 3 :SnO 2 (ITO) and fluorine-doped tin oxide, SnO 2 :F (FTO) are the most common transparent conductive oxides (TCOs) used as transparent back contacts. Generally, higher efficiency is achieved when kesterite is grown on FTO as back electrode because of the In diffusion into CZTSSe layer and the formation of SnO x when using ITO.…”

9.3% Efficient Flexible Cu2ZnSn(S,Se)4 Solar Cells with High‐Quality Interfaces via Ultrathin CdS and Zn0.8Sn0.2O Buffer Layers

“…Flexible Cu 2 ZnSn(S,Se) 4 (CZTSSe) solar cells possess great application potentials with the advantages of soft material, lightweight, and low‐production energy consumption. [ 1–8 ] The CZTSSe solar cells based on flexible Mo foils exhibit excellent flexibility and long‐term stability and maintain the original efficiency after thousands of bending cycles, which have potential applications in noncurved equipment, indoor environment, and so on. [ 9–11 ] However, the current performance of CZTSSe solar cells is limited to their high open‐circuit voltage deficit ( V OC‐def ).…”