Effects of working pressure and power on photovoltaic and defect properties of magnetron sputtered Sb₂Se₃ thin-film solar cells

Abstract

Antimony selenide ( Sb 2 Se 3 ) is an emerging material with potential applications in photovoltaics, while magnetron sputtering is an important method in material growth. In this study, Sb 2 Se 3 thin films, prepared by the magnetron sputtering technique with varied working pressures and sputtering powers, were fabricated into solar cells with a structure of glass / ITO / CdS / Sb 2 Se 3 / Au . The current density versus voltage measurements and x-ray diffraction were introduced to compare the photovoltaic and structural properties of the cell samples. Characterization and identification of the defects in Sb 2 Se 3 thin films were investigated by admittance measurements. The Sb 2 Se 3 cell samples prepared with appropriate sputtering power (about 60 W) or working pressure (about 0.4 Pa) were found to own better crystal qualities and lower defect densities, which may be the reason for better efficiency.

Emerging Chalcogenide Thin Films for Solar Energy Harvesting Devices

“…In 2018, the DLTS was carried out on a 7.6% PCE Sb 2 Se 3 solar cell fabricated by the VTD method . Two kinds of deep acceptor defects with depth of E v +0.48 and E v +0.71 eV and one kind of deep donor defect with depth of E c -0.60 eV were observed. ,− The two acceptors were attributed to V Sb and Se Sb , respectively, and the donor defect was assigned to Sb Se . Similar to Sb 2 S 3 solar cells, the deep defect density in Sb 2 Se 3 was larger than 10 14 cm –3 , which could promote nonradiative recombination, resulting in the short carrier lifetime and large V OC loss .…”

Open-Circuit Voltage Loss of Antimony Chalcogenide Solar Cells: Status, Origin, and Possible Solutions

“…In contrast, the defects of Sb 2 Se 3 solar cells have been comprehensively studied by several groups. 37,43,[60][61][62]65 Two kinds of deep acceptor defects (0.48 and 0.71 eV) and one kind of deep donor defect (0.62 eV) were found in undoped Sb 2 Se 3 solar cells by DLTS characterization. 60,62 Wen et al identified the 0.62 eV defect to antimony antisite (Sb Se ), 0.48 eV defect to antimony vacancy (V Sb ), and 0.71 eV defect to selenium antisite (Se Sb ).…”

“…Since then, no additional literature reports on the defect information in Sb 2 S 3 solar cells have appeared. In contrast, the defects of Sb 2 Se 3 solar cells have been comprehensively studied by several groups. ,,− , Two kinds of deep acceptor defects (0.48 and 0.71 eV) and one kind of deep donor defect (0.62 eV) were found in undoped Sb 2 Se 3 solar cells by DLTS characterization. , Wen et al identified the 0.62 eV defect to antimony antisite (Sb Se ), 0.48 eV defect to antimony vacancy (V Sb ), and 0.71 eV defect to selenium antisite (Se Sb ) . These defects generally have a density of 10 14 –10 15 cm –3 , which is 1–3 orders of magnitude greater than that of CdTe and CIGS solar cells .…”

Defect engineering in antimony selenide thin film solar cells

“…To gain further insight into the specific influence of each defect on the carrier dynamics and defect density states of the absorber, TRTA, time-resolved photoluminescence (TRPL), terahertz (THz) spectroscopy, and angular frequency-dependent capacitance were employed. 7,39,72,79,80,123 The activation energy of the dominant defects (V Sb and Se Sb ) of Sb 2 Se 3 is much larger than that of Sb 2 S 3 and kesterite materials, 78 which means that only 2.6% of the bulk defects of Sb 2 Se 3 contribute to the free carriers, leading to low free carrier density (7.7 × 10 13 cm −3 ), limited bulk conductivity, and small quasi-Fermi level splitting under illumination. The N T values of 6.9 × 10 14 cm −3 and 1 × 10 15 cm −3 were determined from space charge limited current measurement and first-principle calculation for Sb 2 Se 3 films at room temperature, respectively.…”

“…In contrast, defects that introduce levels deep in the bandgap with energy much higher than k B T form deep level defects (Fig. 2(b)) 32,39,72,73 The trap states associated with deep defects usually act as detrimental traps for photogenerated carriers and act as recombination centers and dictate carrier mobility, which ultimately affects the efficiency of the device; thus, the formation of these should be avoided. Fig.…”