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Cu2Ni0·05Zn0·95Sn(S,Se)4 (CNZTSSe) films were synthesized on Mo-coated glass substrates by the simple sol–gel means combined with the selenization process, and CNZTSSe-based solar cells were successfully prepared. The effects of selenization temperature on the performance and the photoelectric conversion efficiency (PCE) of the solar cells were systematically studied. The results show that the crystallinity of films increases as the selenization temperature raises based on nickel (Ni) doping. When the selenization temperature reached 540 °C, CNZTSSe films with a large grain size and a smooth surface can be obtained. The Se doping level gradually increased, and Se occupied the S position in the lattice as the selenization temperature was increased so that the optical band gap (Eg) of the CNZTSSe film could be adjusted in the range of 1.14 to 1.06 eV. In addition, the Ni doping can inhibit the deep level defect of SnZn and the defect cluster [2CuZn + SnZn]. It reduces the carrier recombination path. Finally, at the optimal selenization temperature of 540 °C, the open circuit voltage (Voc) of the prepared device reached 344 mV and the PCE reached 5.16%. [ABSTRACT FROM AUTHOR]

Element doping into the Cu 2 ZnSn(S,Se) 4 (CZTSSe) absorber is an effective method to optimize the performance of thin film solar cells. In this study, the Cu 2 In x Zn 1-x Sn(S,Se) 4 (CIZTSSe) precursor film was deposited by magnetron cosputtering technique using indium (In) and quaternary Cu 2 ZnSnS 4 (CZTS) as targets. Meanwhile, the In content was controlled using the direct current (DC) power on In target (P In). A single kesterite CIZTSSe alloy was formed by successfully doping a small number of In3+ into the main lattice of CZTSSe. The partial Zn2+ cations were substituted by In3+ ions, resulting in improving properties of CZTSSe films. Morphological analysis showed that large grain CIZTSSe films could be obtained by doping In. The well-distributed, smooth, and dense film was obtained when the P In was 30 W. The band gap of CIZTSSe could be continuously adjusted from 1.27 to 1.05 eV as P In increased from 0 to 40 W. In addition, the CIZTSSe alloy thin film at P In = 30 W exhibited the best p-type conductivity with Hall mobility of 6.87 cm2V−1s−1, which is a potential material as the absorption layer of high-performance solar cells. [ABSTRACT FROM AUTHOR]

The Ag-alloyed Cu 1.9 Ag 0.1 ZnSn(S,Se) 4 (CAZTSSe) films were prepared by selenidation of Cu 1.9 Ag 0.1 ZnSnS 4 (CAZTS) precursor films under various selenidation conditions. The effects of selenidation time and selenidation temperature on the composition, morphology, optical band gap (Eg) and device performance of CAZTSSe films were systematically studied. It is found that the selenidation temperature of 480 °C and selenidation time of 10 min provide a favorable selenidation environment for the growth of the film, which can promote grain growth and form a thick and smooth film. This has been strongly confirmed through relevant tests. In addition, the analysis of performance characterization of the films shows that the Eg of the films can be adjusted via adjusting the selenidation conditions, so as to improve the electrical properties. Finally, the CAZTSSe solar cell with a photoelectric conversion efficiency (PCE) of 5.94 % and an open circuit voltage (V oc) of 397 mV was successfully prepared at the selenidation temperature of 480 °C and selenidation time of 10 min. • A new method to improve V oc and PCE of CZTSSe solar cell by Ag doping is put forward. • This is the first report on the effect of post-selenization on CAZTSSe solar cell. • Eg of CAZTSSe can be continuously adjusted by adjusting the selenidation condition. • The effect of selenization condition on PCE is ascribed to change of V OC and FF. • This study shows hopeful character of selenidation condition in increasing the PCE. [ABSTRACT FROM AUTHOR]

In this work, the Cu2MnxZn1−xSn(S,Se)4 (0 ≤ x ≤ 1) (CMZTSSe) alloy films were fabricated by a sol-gel method. Meanwhile, the effects of Mn substitution on the structural, morphological, electrical, optical, and device performance were studied systematically. The clear phase transformation from Cu2ZnSn(S,Se)4 (CZTSSe) with kesterite structure to Cu2MnSn(S,Se)4 (CMTSSe) with stannite structure was observed as x = 0.4. The scanning electron microscope (SEM) results show that the Mn can facilitate the grain growth of CMZTSSe alloy films. Since the x was 0.1, the uniform, compact, and smooth film was obtained. The results show that the band gap of the CMZTSSe film with a kesterite structure was incessantly increased in a scope of 1.024–1.054 eV with the increase of x from 0 to 0.3, and the band gap of the CMZTSSe film with stannite structure was incessantly decreased in a scope of 1.047–1.013 eV with the increase of x from 0.4 to 1. Meanwhile, compared to the power conversion efficiency (PCE) of pure CZTSSe device, the PCE of CMZTSSe (x = 0.1) device is improved from 3.61% to 4.90%, and about a maximum enhanced the open-circuit voltage (VOC) of 30 mV is achieved. The improvement is concerned with the enhancement of the grain size and decrease of the Cu instead of Zn (CuZn) anti-site defects. Therefore, it is believed that the adjunction of a small amount of Mn may be an appropriate approach to improve the PCE of CZTSSe solar cells. [ABSTRACT FROM AUTHOR]

Cation substitution is a promising approach to reduce the antisite defects and further improve the efficiency of Cu2ZnSn(S,Se)4 (CZTSSe) cells. In this paper, silver (Ag) has been introduced into Cu2ZnSn(S,Se)4 (CZTSSe) thin film to replace Cu partially and form (Cu1-xAgx)2ZnSn(S,Se)4 (0 ≤ x ≤ 1) (CAZTSSe) alloy films by combination of solution method and a rapid annealing technique. The fundamental properties of the mixed Ag-Cu kesterite compound are systematically reported as a function of the Ag/(Ag+Cu) ratio. The results show that band gap of kesterite CAZTSSe is incessantly increased by adjusting the Ag doping content, indicating that the CAZTSSe alloy film is a potentially applicable bandgap grading absorption layers material to obtain higher CZTSSe device. Furthermore, CAZTSSe alloy films with better electrical performance were also obtained by adjusting the Ag content during film fabrication. Finally, we also observed an increment in open circuit voltage (Voc) by 160 mV and an accompanying rise in device efficiency from 4.24 to 5.95%. The improvement is correlated to the improved grain size and decreased antisite defects of Cu instead of Zn site (CuZn) in the lattice. The Voc enhancement evidences that the solution method is facile and viable to achieve proper cation substitution toward higher efficiency kesterite solar cells. In addition, the CAZTSSe cell also displays better charge collection performance because of the higher fill factor (FF) and power conversion efficiency (PCE). Therefore, it can be concluded that the doping of Ag is a potentially appropriate method to reduce the Cuzn antisite defects of CZTSSe and improve efficiency of CZTSSe device. [ABSTRACT FROM AUTHOR]

(Na 0.1 Cu 0.9) 2 ZnSn(S,Se) 4 thin films with a single kesterite phase were synthesized using a sol-gel spin-coating method accompanied by rapid post-annealing. In this study, we investigated the effect of selenization time on the crystal quality and photoelectric performance of the (Na 0.1 Cu 0.9) 2 ZnSn(S,Se) 4 films. It was found that the crystallinity and morphology of the films was enhanced, and some of bigger Se substituted for the S site in (Na 0.1 Cu 0.9) 2 ZnSn(S,Se) 4 with increasing the selenization time. The bandgap of the film can be regulated from 1.04 eV to 0.99 eV by varying the selenization time. In addition, all films showed p-type conductive characteristics, and films with optimal electrical performance could be obtained by optimizing the selenization time. Finally, the (Na 0.1 Cu 0.9) 2 ZnSn(S,Se) 4 thin film with the best crystal quality and optical-electrical characteristics was obtained at an optimized selenization time of 15 min. A high power conversion efficiency (PCE) of 3.92% was obtained for the (Na 0.1 Cu 0.9) 2 ZnSn(S,Se) 4 device, which is 42% higher compared to that of the undoped Cu 2 ZnSn(S,Se) 4 (CZTSSe) device. [ABSTRACT FROM AUTHOR]