Microelectronic Structure and Doping Nonuniformity of Phosphorus-Doped CdSeTe Solar Cells.

Optimizing group-V doping and Se alloying are two main focuses for advancing CdTe photovoltaic technology. We report on nanometer-scale characterizations of microelectronic structures of phosphorus (P)-doped CdSeTe devices using a combination of two atomic force microscopy-based techniques, namely, Kelvin probe force microscopy (KPFM) and scanning spreading resistance microscopy (SSRM). KPFM on device cross-section images distribution of the potential drop across the device.

Patterning Metal Grids for GaAs Solar Cells with Cracked Film Lithography: Quantifying the Cost/Performance Tradeoff.

We introduce cracked film lithography (CFL) as a way to reduce the cost of III-V photovoltaics (PV). We spin-coat nanoparticle suspensions onto GaAs thin-film device stacks. The suspensions dry in seconds, forming crack networks that we use as templates through which to electroplate the solar cells' front metal grids.

Macroscopic Nonuniformities in Metal Grids Formed by Cracked Film Lithography Result in 19.3% Efficient Solar Cells.

Cracked film lithography (CFL) is an emerging method for patterning transparent conductive metal grids. CFL can be vacuum- and Ag-free, and it forms more durable grids than nanowire approaches. In spite of CFL's promising transmittance/grid sheet resistance/wire spacing tradeoffs, previous solar cell demonstrations have had relatively low performance.

Fundamentals of Using Cracked Film Lithography to Pattern Transparent Conductive Metal Grids for Photovoltaics.

The fundamentals of using cracked film lithography (CFL) to fabricate metal grids for transparent contacts in solar cells were studied. The underlying physics of drying-induced cracks were well-predicted by an empirical correlation relating crack spacing to capillary pressure. CFL is primarily controlled by varying the crack template thickness, which establishes a three-way tradeoff between the areal density of cracks, crack width, and spacing between cracks, which in turn determine final grid transmittance, grid sheet resistance, and the semiconductor resistance for a given solar cell.

Soft X-ray Spectroscopy of a Complex Heterojunction in High-Efficiency Thin-Film Photovoltaics: Intermixing and Zn Speciation at the Zn(O,S)/Cu(In,Ga)Se Interface.

The chemical structure of the Zn(O,S)/Cu(In,Ga)Se interface in high-efficiency photovoltaic devices is investigated using X-ray photoelectron and Auger electron spectroscopy, as well as soft X-ray emission spectroscopy. We find that the Ga/(Ga+In) ratio at the absorber surface does not change with the formation of the Zn(O,S)/Cu(In,Ga)Se interface. Furthermore, we find evidence for Zn in multiple bonding environments, including ZnS, ZnO, Zn(OH), and ZnSe.