Failure and Recovery Modes of Submicron Cu(In,Ga)Se₂ Solar Cells with High Cu Content

Abstract

As an emerging route to further lower the production cost, reducing the thickness of Cu(In,Ga)Se 2 (CIGS) absorber has drawn substantial attention and has been intensively studied in recent years. However, thickness-induced change still limits the device performance of thin CIGS solar cells. Herein, by examining a series of submicron CIGS solar cells with varied Cu content through their photovoltaic (PV) performance, the optimal Cu content in these submicron CIGS devices is found to be lower than that of the normal thickness CIGS devices. Electrical and compositional characterizations reveal that reduced thickness makes absorber vulnerable to the shunt paths formed with high Cu content. By intentionally lowering the Cu content in submicron CIGS, shunt resistance (R sh ) of the devices is significantly improved and therefore a high fill factor (FF) is achieved. Moreover, RbF postdeposition treatment (PDT) can passivate the shunt paths in the high Cu content samples to a very good extent, manifesting by the significantly improved FF.

Over 16% Efficient Solution‐Processed Cu(In,Ga)Se2 Solar Cells via Incorporation of Copper‐Rich Precursor Film

“…For Cu‐rich CIGS devices, the absence of a Cu‐deficient layer and an additional (NH 4 ) 2 S solution etching process inhibits the device performance and application, respectively. [ 23 ] Therefore, it is essential to design an efficient and novel technique that is appropriate for solution‐processed CIGS film with the goal of producing large grain and low‐defect CIGS film.…”

8.0% Efficient Submicron CuIn(S,Se)2 Solar Cells on Sn:In2O3 Back Contact via a Facile Solution Process

“…Thinner absorber layers result in low cost because they reduce material consumption and increase production throughput. However, the efficiency of thin absorbers is limited by electrical and optical losses, such as increased recombination at back contact and reduced light absorption. − , As shown in the previous section, the best solar cell properties are obtained for absorbers selenized at 520 °C, thus T = 520 °C will be used for exploring the effect of absorber thickness. Three absorber thicknesses are utilized for the investigations: 550 nm (ultrathin absorber), 740 nm (submicron absorber), and 1440 nm (micron absorber).…”

Rear Interface Engineering in Solution‐Processed Submicron Cu(In,Ga)(S,Se)2 Solar Cells on Transparent Sn:In2O3 Back Contact

“…In addition, a submicron CIGSSe absorber can reduce the pathway for electron/hole extraction and improve the homogeneity of the absorber and therefore is promising for cost-effective and efficient solar cells. [5] Typically, molybdenum (Mo) is used as a back contact material for various chalcogenide thin film solar cells due to the formation of the favorable quasi-Ohmic contact at the absorber/Mo interface. However, the Mo back contact has strong parasitic absorption, leading to an increase in optical losses for submicron cells.…”