Grain Growth Mechanism of CZTSSe Films Controlled by the Evaporation Area of Se

Abstract

Thermally evaporated Se, including the molecules of Se2, Se5, Se6, Se7, and Se8 in the vapor at 550–600 °C, is widely used for the selenization of CZTSSe films. However, active small‐molecule Se2 tends to form large clusters of Se atoms at saturation vapor pressure, resulting in the large Se deficiency and poor crystallization of CZTSSe films. To regulate the time for Se to reach saturation vapor pressure and promote the role of active small‐molecule Se, the evaporation area of Se is controlled. Then the corresponding grain growth mechanism of CZTSSe films and device efficiency are systematically investigated. The results demonstrate that the appropriate evaporation area of Se can not only optimize the time for Se vapor to reach saturation, promote the rapid reaction crystallization between the precursor films and active Se2, but also inhibit the nucleation at the CZTSSe/Mo interface, thus making the CZTSSe films show a perfect top‐down grain growth mode. By preliminary optimization, when the evaporation area of Se is 245 mm2, a large‐grain spanning monolayer CZTSSe thin film is obtained; meanwhile, a device with a high efficiency of 12.39% is achieved. This study provides a new selenization strategy for improving the crystallinity of CZTSSe thin films.

Element Diffusion Induced Carrier Transport Enhancement in High‐Performance CZTSSe Self‐Powered Photodetector

“…The obtained R S , J 0 , and G values show the excellent performance of heterojunction diode. Especially, the G value is closed to the reported values in the literatures, [17] which indicates less leakage current of CZTSSe PDs. The logarithmic J-V curves under dark at room temperature are shown in Figure 3a.…”

Interface-suppressed high-quality symmetrical bifacial flexible CZTSe solar cells through a green electrodeposition process

“…35 The dominant recombination path can be estimated from the following equation:where A , J 0 , J 00 , E a , K , and T represent the ideal factor, reverse saturation current density, prefactor depending on recombination paths, recombination activation energy, Boltzmann constant, and temperature, respectively. 34–36 The difference between E a and E g was used to explain the dominant recombination path. If E a is close to or equal to E g , Shockley Reid Hall (SRH) recombination in the neutral region is dominant.…”

“…J-V-T analysis is generally used to determine the dominant recombination path in kesterite-based solar cells. 34,35 A dark J-V-T analysis was conducted from 120 to 300 K, as shown in Fig. 5f, to clarify the key factors affecting the efficiency of our devices.…”

Regulating Air‐Annealing Time for Boosting the Performance of Cu2ZnSn(S, Se)4 Solar Cells

“…[20][21][22] In order to avoid this embarrassing situation, many researchers are dedicated to improve the CZTSSe crystal quality based on these ecofriendly solution methods. [22][23][24][25][26][27][28] Recently, an air-baking optimization is employed to gift the absorber excellent crystal quality and give the device high efficiency. Pan et al proposed that air baking before selenization can contribute to Na incorporation and O absorption on the film, helping the crystallinity of CZTSSe absorber and enhancing the photoelectric conversion efficiency (PCE) of devices to 9.8%.…”