Atomic layer deposited ZnxNi1−xO: A thermally stable hole selective contact for silicon solar cells

Abstract

Atomic layer deposited zinc nickel oxide (ZNO, ZnxNi1−xO) films with Zn concentrations of 0.09, 0.46, and 0.62 are investigated for application as a hole-selective contact for crystalline silicon solar cells. The ZNO films were found to be p-type by evaluating their contact performance on p-Si. A direct contact between ZNO and p-Si showed perfect ohmic behaviour. Spectroscopic ellipsometry measurements revealed a high optical transparency of the ZNO films with a bandgap of >3 eV. X-ray photoelectron spectroscopy confirmed a much lower valence band offset between ZNO and p-Si than the conduction band offset, which is favourable for selective hole extraction on p-Si. In addition, subsequent annealing at 200 °C significantly decreased the contact resistivity, and annealing temperatures up to 500 °C did not degrade its contact performance. A minimal contact resistivity of 21.5 mΩ·cm2 was obtained on p-type c-Si for a 3.4 nm ZNO film with a Zn concentration of 0.62 after annealing at 200 °C. These results demonstrate the advantages of ZnxNi1−xO as a hole-selective contact for crystalline p-Si solar cells.

Work Function Tunability of Graphene with Thermally Evaporated Rhenium Heptoxide for Transparent Electrode Applications

“…[25][26][27][28] The recent investigations of hole transport layers suggest a new class of materials for modification of graphene properties with aim of application in optoelectronics. [29][30][31][32][33][34][35][36][37][38][39] Particularly, heterostructures made of graphene and thin transition metal oxide (TMO) films seem to be very attractive in optoelectronics and may play the role of hole or electron injection layers (HIL/EIL). [17,18,29] TMOs' electronic structures include empty d-bands, partially filled d-bands with low/high occupancy, and full d-bands classes.…”

“…Nevertheless, the desired functionality of graphene in a wide range of fields is gained when graphene is combined with another class of materials, resulting in the formation of composite materials with improved properties . The recent investigations of hole transport layers suggest a new class of materials for modification of graphene properties with aim of application in optoelectronics . Particularly, heterostructures made of graphene and thin transition metal oxide (TMO) films seem to be very attractive in optoelectronics and may play the role of hole or electron injection layers (HIL/EIL) .…”

Recent Advances in Materials Design Using Atomic Layer Deposition for Energy Applications

“…The development of hole‐selective TMOs contact for c‐Si solar cells is less mature compared to its electron‐selective counterpart. While a few TMOs, such as MoO 3 , [ 50 ] WO 3 , [ 50b ] V 2 O 5 , and NiO, [ 51 ] have shown their potential as passivating hole contacts on c‐Si, MoO 3 is the most successful and heavily explored material in c‐Si solar cells (Table 1). This is evidenced by an SHJ device with a thermally evaporated 4 nm MoO 3 layer with 8 nm a‐Si:H interlayer with an efficiency of 23.5%.…”

High‐Efficiency Nonfullerene Organic Solar Cells Enabled by Atomic Layer Deposited Zirconium‐Doped Zinc Oxide

“…Al‐doped ZnO has been the most commonly used material including in Si solar cells for its application as a transparent conductive oxide and as an ETL. [ 40–42 ] Other dopants, such as Mg, [ 43 ] Ni, [ 44 ] B, [ 45,46 ] Co, [ 47 ] Zr, [ 48,49 ] Ge, [ 50 ] Hf, [ 51 ] Sn [ 52 ] have also been investigated. Among these dopants, Zr 4+ (0.84 Å) has the comparable ionic size to Zn 2+ (0.74 Å) and the ability to donate two electrons with minimum lattice distortion into the ZnO host lattice.…”