Influence of Oxygen on Sputtered Titanium‐Doped Indium Oxide Thin Films and Their Application in Silicon Heterojunction Solar Cells

Abstract

Considering the increasing global energy demand, solar cells that directly convert light into electricity offer a realistic and sustainable solution to the challenge of providing renewable energy. Improving energy conversion efficiency (η) and reducing the fabrication cost are two main directions to promote the application of c-Si solar cells. As one of the most promising solar cell structures, silicon heterojunction (SHJ) solar cells provide a promising solution for mass production due to their excellent device performance with a small temperature coefficient. [1-4] A well-known advantage of SHJ solar cells is the high open-circuit voltage (V oc), which can be achieved by the suppression of minority carrier recombination at the surface of c-Si with hydrogenated amorphous silicon (a-Si:H) passivation layers. [5,6] For a highefficiency solar cell, not only a high V oc but also a high fill factor (FF) and a high short-circuit current density (J sc) are mandatory. In SHJ solar cells, the role of transparent conductive oxide (TCO) layers is to collect charge carriers separated by the p-n junction and to act as an antireflection coating that allows more light to be absorbed in the silicon wafer for current generation. [7-9] These two aspects directly affect FF and J sc , respectively.

Transparent Conductive Oxide Sputtering Damage on Contact Passivation in Silicon Heterojunction Solar Cells with Hydrogenated Nanocrystalline Silicon

“…[ 23 ] The front total contact resistivity was determined by the transfer‐length method (TLM) with a specific pattern, details of which can be found in ref. [24,25] To evaluate the solar cells performance, current–voltage ( J – V ) characteristics were measured under standard test conditions (AM1.5, 25 °C, and 100 mW cm −2 ) by the LOANA system from pv‐tools with a Wavelabs Sinus 220 light source. The external quantum efficiency (EQE) and reflectance ( R ) were measured on a 20 20 mm 2 area of the cells with grids inside.…”

Efficient monolithic perovskite–Si tandem solar cells enabled by an ultra-thin indium tin oxide interlayer

“…39 For example, the resistivity of our ITO at 100 nm is 4.28 Â 10 -4 O cm (R SH =42.8 O per square) while for ITO normally used in a SHJ solar cell, the resistivity is around 1.61 Â 10 À3 O cm for a 70 nm thick layer Table 1 Characteristics of Si-perovskite 1 cm 2 tandem test cells with varying ITO interlayer thicknesses prior to the application of anti-reflection layers Energy & Environmental Science Paper (R SH = 230 O per square). 39 This can result in the formation a strong Schottky contact between the ITO and hpia-Si:H layers leading to a depletion of charge carriers in the hpia-Si:H and therefore a reduction in the built-in potential. 40 This needs to be compensated by the increase in the thickness of the hpia-Si:H junction to increase the built-in potential back to desired levels.…”

Toward Efficiency Limits of Crystalline Silicon Solar Cells: Recent Progress in High‐Efficiency Silicon Heterojunction Solar Cells

“…By SPC processes, I 2 O 3 :H layers are first deposited at low temperatures (room temperature) in an amorphous matrix and subsequently annealed at temperatures ≈170 °C. Recently, high-mobility and thin NIR-transparent In 2 O 3 films have been produced by doping metals such as Cerium, [88,89] Titanium, [90] and Zirconium, [91] which perform as transparent electrodes for solar cells having sensitivity in the visible to the NIR wavelength region. [92] With higher carrier mobility (>100 cm 2 V −1 s −1 ), In 2 O 3 :Ce, In 2 O 3 :Ti, and In 2 O 3 :Zr are promising TCO candidates for SHJ solar cell production.…”

“…Approach for higher J SC Optimization of a-Si:H Wide bandgap carrier transport layers a-SiC:H, [70] a-SiO X :H, [71,73] nc-SiC:H, [72] nc-SiO X :H [75][76][77][78] Indirect bandgap carrier transport layers nc-Si:H [68,69] Optimization of TCO Higher mobility TCO layers I 2 O 3 :W, [84,85] I 2 O 3 :H, [86,87] In 2 O 3 :Ce, [88,89] In 2 O 3 :Ti, [90] In 2 O 3 :Zr [91] TCO/SiO x (SiN x ) composite layers a-SiO 2 /TCO, [93] SiO X /I 2 O 3 :W, [98] SiN/ITO [97] TCO-free SHJ Front TCO-free SHJ solar cells [96] Reduction of grid shadowing…”