Single vacuum chamber with multiple close space sublimation sources to fabricate CdTe solar cells

Abstract

Photovoltaic technologies have shown efficiencies of over 40%, however, manufacturing costs have prevented a more significant energy market penetration. To bridge the gap between the high efficiency technology and low cost manufacturing, a research and development tool and process was built and tested. This fully automated single vacuum photovoltaic manufacturing tool utilizes multiple inline close space sublimation (CSS) sources with automated substrate control. This maintains the proven scalability of the CSS technology and CSS source design but with the added versatility of independent substrate motion. This combination of a scalable deposition technology with increased cell fabrication flexibility has allowed for high efficiency cells to be manufactured and studied. The single vacuum system is capable of fabricating a 3.1 × 3.6 in. substrate every 45 min with a cell efficiency of 12% with a standard deviation of 0.6% as measured over 36 months. The substrate is generally scribed into 25 small area devices allowing for over 250 small area devices to be fabricated each day. The system can operate uninterrupted for maintenance for over 21 days.

Polycrystalline CdSeTe/CdTe Absorber Cells With 28 mA/cm2 Short-Circuit Current

“…CdSeTe films were sublimated using an optimized deposition process followed by sublimation of the CdTe layer. The CdSe x Te 1-x (CdSeTe) and CdTe depositions were followed by CdCl 2 passivation, performed in-line without breaking vacuum [10]. The substrate was heated to about 540ºC before starting the sublimation of CdSeTe.…”

Intragranular defects in As-deposited and cadmium chloride-treated polycrystalline cadmium telluride solar cells

“…Thin-film CdTe solar cells were fabricated using close space sublimation (CSS) in an all-in-one vacuum process as detailed in [12]. One of the samples was exposed to a CdCl 2 activation treatment, while the second was left untreated.…”

CdTe Photovoltaics for Sustainable Electricity Generation

“…11 Deposition of CdS and CdTe layers and CdCl 2 passivation treatment are carried out using closed-space sublimation from sources integrated into a single-vacuum system. 6,12 Thereafter, the substrate is transferred to another tool for co-sublimation of Cd 1Àx Mg x Te which would create the conduction band offset due to its higher band gap. This tool allows for similar temperature control as the ARDS and the substrate here is preheated before the deposition of Cd 1Àx Mg x Te is carried out.…”

“…Figure 2 shows a schematic diagram of the advanced research deposition system (ARDS) used to fabricate the thin film CdTe photovoltaic devices. 6 The ARDS allows repeatable fabrication of up to 8-10 substrates per day, of which 25 research-scale devices may be fabricated and characterized. The advanced control on the ARDS allows alterations in the deposition sequence as well as the time for which the substrate stays in each deposition source to be precisely controlled up to as little at 1 s. The ARDS deposition sources have bottom and top heaters made using nichorme coils.…”

“…Schematic of the various layers that make a baseline cell structure of a typical CdS/CdTe cell fabricated using a single vacuum chamber 6. …”