Interface stoichiometry control in ZnO/Cu<inf>2</inf>O photovoltaic devices

Abstract

Cu2O is a potential earth-abundant alternative to established thin photovoltaic materials (CIGS, CdTe, etc.) because of its low cost, high availability, and inexpensive processing, but Cu2O has seen limited development as a photovoltaic device material owing to challenges in measurement and control of interface stoichiometry and doping. We report measurements of Cu2O interface stoichiometry and the effect of interface composition on heterojunction device performance. ZnO/Cu2O interface stoichiometry was varied by adjusting the ZnO window layer deposition conditions and stoichiometry was measured by X-ray photoelectron spectroscopy. Current-voltage characteristics of ZnO/Cu2O heterojunctions indicate open circuit voltages of Voc ~ 530 mV for devices where the Cu2O layer is stoichiometric at the interface and Voc ~ 100 mV for devices where Cu2O is nonstoichiometric at the interface.

Interface stoichiometry control to improve device voltage and modify band alignment in ZnO/Cu2O heterojunction solar cells

“…2,3,[15][16][17][18][19][20][21][22] In this manuscript, we describe the controlled modication of ZnO/Cu 2 O heterostructures to yield stoichiometric interfaces as well as nonstoichiometric interfaces with Cu and CuO present. We also show that stoichiometric interfaces are necessary for achieving large device voltages.…”

“…We have chosen to study the ZnO/Cu 2 O interface because it has been the most widely studied Cu 2 O based heterostructure, and until recently, the most efficient heterojunction system as well. 2,3,[15][16][17][18][19][20][21][22] In this manuscript, we describe the controlled modication of ZnO/Cu 2 O heterostructures to yield stoichiometric interfaces as well as nonstoichiometric interfaces with Cu and CuO present. We also show that stoichiometric interfaces are necessary for achieving large device voltages.…”

Atomic Layer Deposited Gallium Oxide Buffer Layer Enables 1.2 V Open‐Circuit Voltage in Cuprous Oxide Solar Cells

“…In addition, the chemical state of Cu at the interface is identified by XPS to investigate the defect density at the Ga 2 O 3 /Cu 2 O interface. The Cu 2+ ‐related state at the interface has been considered to create deleterious traps that promote interface recombination . Figure b shows the XPS spectra of the Cu‐2 p core levels of the Ga 2 O 3 /Cu 2 O stack sample and an as‐grown Cu 2 O bulk sample.…”