Preparation and characterization of monolithic HgCdTe/CdTe tandem cells

Abstract

A prototype monolithic HgCdTe/CdTe superstrate tandem cell has been fabricated by RF sputtering, comprising a CdTe/CdS top cell, a ZnTe:N/ZnO:Al interconnect junction and a HgCdTe/CdS bottom cell. The Hg 1-x Cd x Te film as the bottom absorption layer was deposited by RF sputtering with 70% or 85% Cd content in the Hg 1-x Cd x Te magnetron target. Hg 1-x Cd x Te films with band gap from 0.98 eV to 1.45 eV were obtained by controlling the deposition temperature. CdCl 2 thermal treatments were used to improve the Hg 1-x Cd x Te film electrical properties. A nitrogen-doped ZnTe film combined with an aluminium (Al) doped ZnO film formed a good interconnect junction. Results of V oc = 0.99 V and J sc = 2.1 mA /cm 2 were obtained in the best such tandem cell at one sun (AM1.5).

Tandem Solar Cells from Solution-Processed CdTe and PbS Quantum Dots Using a ZnTe–ZnO Tunnel Junction

“…In our study, we seek to construct a monolithic CdTe–PbS QD tandem solar cell combining these two nanocrystal-based absorbers in series using CdTe as the top cell. We evaluate a variety of device structures for CdTe nanocrystal-based solar cells and adopted the structure that yields the highest open-circuit voltage ( V oc ) and had the optimal polarity configuration to match the PbS solar cells. ,, We developed a recombination layer of ZnTe–ZnO similar to Wang et al and reliably obtain a V oc in excess of 1 V, indicating proper addition of the V oc of the subcells with short-circuit current density ( J sc ) of 10 mA/cm 2 with overall power conversion efficiency of 5%.…”

Comparison of transparent back contacts for CdTe top cells in tandem thin-film photovoltaic devices

“…Control devices with a Ti metallization were defined to 0.25-cm 2 area. An aqueous solution of 39% FeCl3 was used to etch the ZnO:Al, ZnTe:Cu, and CdTe between the patterned devices.…”

“…CdTe, however, with its slightly lower bandgap of 1.5 eV, can function effectively as a top cell when paired with, for example, a HgxCd1-xTe bottom cell of appropriate bandgap [2]. The two photovoltaic (PV) devices may be grown monolithically or mechanically stacked.…”

Structural, optical and electrical characterization of HgxCd1‐xTe polycrystalline films fabricated by two‐source evaporation technique

“…Thin layers of MCT on conducting/nonconducting substrates are normally required for many applications [8]. This material has been grown by different techniques [17][18][19][20][21][22][23]. The thermal evaporation is considered to be a standard and reproducible method for most thin film materials.…”