| Work Detail |
Scientists at TU Delft (Netherlands) used plasma boron ionization (PTB) to build heterojunction solar cells based on a hole transport layer made of thin films of transition metal oxides (TMOs). The device showed a significant balance between the number of defects and carrier transport and achieved remarkable efficiency levels.
Scientists at Delft University of Technology (Netherlands) have fabricated an n-type silicon heterojunction (SHJ) solar cell based on a hole transport layer (HTL) made of thin films of transition metal oxides (TMO).
In the article “ Universal interface engineering method for applying transition metal oxides in silicon heterojunction solar cell,” published in Solar Energy Materials and Solar Cells , the researchers note that TMO materials have a wide bandgap and are used in heterojunction photovoltaic devices to increase their short-circuit current.
“This work presents a successful application of interface engineering methods to improve the performance of SHJ solar cells using polytungstate (WOx) and vanadium suboxide (V2Ox) thin films,” lead author Liqi Qao told pv magazine . “By precisely controlling the oxygen content in the TMO films, we mitigated the detrimental interface reactions between the TMOs and silicon passivation layers, resulting in improved solar cell efficiency.”
The scientists selected these two materials because they “strike” a balance between the amount of oxygen vacancies and their selective transport capacity. They applied plasma boron (PTB) treatment to alleviate the interface reaction of the TMO with the substrate by interface engineering.
This treatment appears to modify the oxygen content in the TMO films, thereby improving their electronic properties.
The group constructed a WOx-based cell and a V2Ox-based device. In the first cell, the thickness of the WOx film was 2 nm, while the V2Ox layer used in the second device was 2 nm thick.
Both 2 cm × 2 cm devices were based on 4-inch floating zone (FZ) wafers processed in tetramethylammonium hydroxide (TMAH) solution, hydrogenated amorphous silicon (a-Si:H) stacks, and a magnesium fluoride (MgF2)-based antireflection coating.
Tested under standard lighting conditions, the WOx-based cell was able to achieve a power conversion efficiency of 23.30% and a fill factor of 80.80%. The other device achieved values ??of 22.04% and 74.88%, respectively.
“The results from our TMO-based FJ-SHJ [front-end silicon heterojunction] solar cells reveal that PTB is a method that creates optimal surface conditions for TMO deposition and achieves a desirable balance between the amount of defects and carrier transport in the film, leading to the improved performance of TMO-based SHJ solar cells,” the researchers conclude. |
