Analysis of a novel CuCl₂ back contact process for improved stability in CdTe solar cells

Abstract

One of the crucial points in the production of CdTe solar cells is the insertion of copper in the back contact and in the absorber. As demonstrated by the top performing devices presented in literature: copper is necessary for high efficiency devices. However, despite this, copper was found to be a fast diffuser degrading the cell in the long term. Different approaches for limiting this effect have been widely presented from several laboratories, from the preparation of CuxTe by the controlled evaporation of Cu and Te to the application of ZnTe, which incorporates Cu, blocking its diffusion in the bulk. We have developed a wet deposition method for inserting in the CdTe structure a quantity of copper equivalent to a 0.1‐nm‐thick Cu layer. We are able to reach similar efficiencies to the ones of devices with a standard 2‐nm‐thick evaporated copper layer, but with a dramatic improvement in performance stability.

Back contacts materials used in thin film CdTe solar cells—A review

“…CuI has also been used as a perovskite HTM. 15 Copper (II) chloride has been used by Artegiani et al (2019). 201 In this case, the copper halide is thought to be acting as a reproducible source for a very small amount of copper (equivalent to 0.1 nm of pure copper) leading to an improvement in device stability after 1000 hours of 80°C stress testing.…”

Effects of Cu Precursor on the Performance of Efficient CdTe Solar Cells

“…Recently, CuCl 2 was incorporated in the CdTe absorber as the Cu precursor to eliminate the diffusion of Cu into the front junction, achieving a maximum PCE of ∼16%. 22 Sites and coworkers have demonstrated a record PCE of 19.1% for CdSeTe solar cells using the CuCl precursor deposited by close space sublimation (CSS). 5,24 We previously reported a PCE of 17.5% for CdTe solar cells (no selenium) using a solution-processed CuCl treatment with rapid thermal anneal- ing process.…”

Metal Chalcogenides (MxEy; E = S, Se, and Te) as Counter Electrodes for Dye–Sensitized Solar Cells: An Overview and Guidelines

“…The corresponding FDSSCs achieved the current highest record PCE of 10.28% for FDSSCs, and outstanding flexibility. The advantages observed for metal selenide-based CEs in FDSSCs were also observed for other metal chalcogenides such us metal sulfides [95,97] and metal tellurides [171][172][173][174][175][176][177][178][179][180] when incorporated in fibrous or flexible PV devices. Chen et al [97] prepared both a CoNi 2 S 4 nanoribbon on CFs (CoNi 2 S 4 nanoribbon-CFs), and a CoNi 2 S 4 nanorod on CFs (CoNi 2 S 4 nanorod-CFs) for use as CEs in FDSSCs.…”

“…As for metal tellurides, they were mostly used in nonfibrous flexible solar cells using polymer substrates (Figure 8b). [171][172][173][174][175][176][177][178][179][180] Some of the most remarkable research works conducted on this topic were from Rance et al [176] and Mahabaduge et al, [177]…”