Conductive Cuprous Iodide Hole-Selective Contacts with Thermal and Ambient Stability for Silicon Solar Cells

Abstract

Dopant-free carrier-selective contacts are becoming increasingly attractive for application in silicon solar cells because of the depositions for their fabrication being simpler and occurring at lower temperatures. However, these contacts are limited by poor thermal and environmental stability. In this contribution, the use of the conductive high work function of cuprous iodide, with its characteristic thermal and ambient stability, has enabled a hole-selective contact for p-type silicon solar cells because of the large conduction band offset and small valence offset at the CuI/p-Si interface. The contact resistivity (≈30 mΩ•cm 2 ) of the Ag/CuI (20 nm)/p-Si contact after annealing to 200 °C represents the CuI-based hole-selective contact with low resistance and high thermal stability. Microscopic images and elemental mapping of the Ag/CuI/p-Si contact interface revealed that a nonuniform, continuous CuI layer separates the Ag electrode and p-type Si. Thermal treatment at 200 °C results in the intermixing of the Ag and CuI layers. As a result, the 200 °C thermal process improves the efficiency (20.7%) and stability of the p-Si solar cells featuring partial CuI hole-selective contact. Furthermore, the devices employing the CuI/Ag contact are thermally stable upon annealing to temperatures up to 350 °C. These results not only demonstrate the use of metal iodide instead of metal oxides as hole-selective contacts for efficient silicon solar cells but also have important implications regarding industrial feasibility and longevity for deployment in the field.

Heterostructures Based on g-C3N4/CuI as a Photoactivated Support for Pt Nanoparticles toward Efficient Photoelectrocatalytic Methanol Oxidation

“…Furthermore, the arcs gradually return to the first quadrant owing to the absence of intermediate species at a higher potential (Figure 6C). 23,36 Moreover, the almost similar variation tendency for the Pt/g-C 3 N 4 /CuI modified electrode under dark conditions is obtained while the DSA is larger at the same potential (Figure 6D−F), indicating the improved interfacial electron transfer under visible light irradiation. Long lifetime stability is another critical factor for the actual practice of photoelectrocatalysts.…”

“…More significantly, the nitrogen-rich structure in the g-C 3 N 4 matrix imparts abundant reactive sites for the hybridization with another semiconductor component, which is conducive to the formation of heterostructures. Cuprous iodide (CuI) is a typical p-type inorganic semiconductor with a wide band gap as the hole transport layer (HTL) candidate, whose applications in transporting holes had received considerable attention in the optoelectrical device field. − When the fascinating physiochemical properties of n-type g-C 3 N 4 are combined with p-type CuI to construct heterostructures, the efficacious charge separation efficiency and enhanced catalytic performance are possibly acquired.…”

Dopant‐Free Bifacial Silicon Solar Cells

“…Therefore, extensive efforts have been devoted to the improvement of silicon solar cells with dopant‐free passivating contacts. [ 4–9 ] By replacing a‐Si:H(p) with a 4 nm thick hole‐collecting and transparent molybdenum oxide (MoO x ) layer, a remarkable solar cell efficiency of 23.5% was recently demonstrated. [ 10 ] The integration of an a‐Si:H(i)/LiF x /Al electron selective contact at the rear side, instead of a‐Si:H(i)/ a‐Si:H(n)/ITO/Ag, [ 11 ] enabled the development of a fully dopant‐free silicon solar cell without any doped a‐Si:H layers or diffused p–n junctions.…”

“…One approach to realize dopant‐free bifacial silicon solar cells consists of using partial area electron‐selective contacts. [ 2,7,8,19,25 ] In work by Zhong et al, an a‐Si:H(i)/ZnO/LiF x /Al contact exhibited a J 0 of 3.5 fA cm −2 and ρ c of 0.136 Ω cm 2 . [ 12,30 ] In that case, the contact resistance is potentially low to form a partial‐area heterocontact for dopant‐free bifacial silicon solar cells with a metal contact fraction between 10% and 50%.…”

Sputter Deposition of Transition Metal Oxides on Silicon: Evidencing the Role of Oxygen Bombardment for Fermi‐Level Pinning

“…Recently, the interest in interfacing TMOs with silicon has substantially increased. Silicon/TMO structures can be encountered not only in water‐splitting devices where the TMO layer is a catalytic layer, but also in solid‐state junction where the TMO layer could be implemented for creating a charge‐selective contact. For instance, n‐type materials as TiO 2 and ZnO could be implemented to create electron‐selective contacts on silicon, whereas p‐type materials or high‐work‐function materials, such as MoO 3 , WO 3 , V 2 O 5 , and NiO, could be implemented to create hole‐selective contacts .…”