Cracked Film Lithography with CuGaO_x Buffers for Bifacial CdTe Photovoltaics

Abstract

sun front illumination efficiency). The backsheet is then replaced with glass at an added cost of only $0.01/W DC,peak for PERC modules. These simple process changes lead to projections of ≈10% more power output over the lifetime of the module, [3] although 5-33% bifacial power gains have been reported. [4] In parallel with the expansion of bifacial PV, the thin-film PV market has also transformed: CdTe accounted for just 2.5% of total and 70% of thin-film shipped capacity in 2017, but these percentages rose to 3.9% of total and 97% of thin-film in 2021. [5] In contrast to mono-Si, none of the deployed or projected bifacial capacity currently includes CdTe modules. To mitigate climate change, CdTe is preferred because it has much lower embodied energy and CdTe manufacturing is less carbon-intensive than mono-Si PV. [6] Due to the technical complications involved in making CdTe bifacial, it typically only has bifaciality of 10-20%, [7,8] and bifacial adaptations have only been demonstrated on relatively low quality absorbers (up to 14.3% front-illumination-efficiency [9] while monofacial CdTe record efficiency is 22.1% [10] ). Transparent CdTe back contact performance is limited by front illumination fill factor (FF), with values only up to 70.8% [11] in the literature. Ideally, bifacial CdTe would start with a high baseline efficiency and then minimize front-side illumination losses. There are three main challenges in making CdTe bifacial:

Flexible Embedded Metal Meshes by Sputter-Free Crack Lithography for Transparent Electrodes and Electromagnetic Interference Shielding

“…Despite these increases in sheet resistance, the impact on the EMI SE was not significantly pronounced (Figure 7b). After the bending tests, the average SE for samples 1 through 5 changed The following works in the literature are shown: Cu mesh(Liu), 67 Ag mesh (Cui), 68 graphene/Ni mesh, 32 Ti/Ag meshes, 73 Ag mesh (Han), 69 Ag mesh (Rao and Gupta), 76 Ag mesh (Xian), 71 Ag mesh (Gupta), 79 Ag mesh (Rao and Hunger), 80 Au mesh (Guo), 81 Ag mesh (Kang), 74 Au mesh (Muzzillo), 70 and Ag mesh (Voronin). from 42.5 to 41.4, from 42.0 to 39.5, from 37.4 to 35.6, from 39.7 to 37.6, and from 38.3 to 38.1 dB, respectively.…”

“…(a) Transmission at 550 nm versus sheet resistance and (b) σ DC /σ OP versus sheet resistance. The following works in the literature are shown: Cu mesh­(Liu), Ag mesh (Cui), graphene/Ni mesh, Ti/Ag meshes, Ag mesh (Han), Ag mesh (Rao and Gupta), Ag mesh (Xian), Ag mesh (Gupta), Ag mesh (Rao and Hunger), Au mesh (Guo), Ag mesh (Kang), Au mesh (Muzzillo), and Ag mesh (Voronin) …”

“…66 Fabricating a metal mesh using crack lithography typically involves five main steps: preparing a colloidal solution or gel film, applying it to the substrate, allowing cracks to form due to induced stresses, depositing a metallic film, and finally removing the crack template. Common materials used for crack template films include acrylic resin, 67,68 SiO 2 or TiO 2 nanoparticle-based dispersions, 32,69 poly(methyl methacrylate), 70 and egg white. 58,71 Most studies in this field have utilized sputtering to form a conductive metallic film.…”

“…Transparent electrode performance of PET-embedded Ag meshes for our five samples compared to that of other crack lithography metal meshes in the literature. (a) Transmission at 550 nm versus sheet resistance and (b) σ DC /σ OP versus sheet resistance.The following works in the literature are shown: Cu mesh(Liu),67 Ag mesh (Cui),68 graphene/Ni mesh,32 Ti/Ag meshes,73 Ag mesh (Han),69 Ag mesh (Rao and Gupta),76 Ag mesh (Xian),71 Ag mesh (Gupta),79 Ag mesh (Rao and Hunger),80 Au mesh (Guo),81 Ag mesh (Kang),74 Au mesh (Muzzillo),70 and Ag mesh(Voronin) 58.…”

Hierarchical Transparent Back Contacts for Bifacial CdTe PV

“…9 Recently, Muzzillo et al demonstrated a combined CuGaO x and templated Au nanogrid contact with 19.2% frontside efficiency and 2.5% backside efficiency. 10 This hierarchical approach is extended in this work to use a copper-free AlGaO x buffer layer, a conductive and semitransparent Ti 3 C 2 T x interlayer with a high work function, and a highly conductive patterned gold nanogrid grid to lower series resistance. Solution-processed AlGaO x hole transport layers have a tunable band gap based on the ratios of aluminum and gallium precursors.…”