Thin Film Solar Cell Based on ZnSnN₂/SnO Heterojunction

TLDR

In this article, we report the growth of zinc‑tin nitride (ZnSnN₂) thin films as a potential absorber for photovoltaic applications by fabricating a heterojunction of n‑ZnSnN₂/p‑SnO, and discuss prime strategies to improve solar cell efficiency concerning band offsets and band alignment engineering. The heterojunction performance was monitored by selectively depositing top electrodes (Ni/Au or Al), and electron transfer from ZnSnN₂ to the cathode is facilitated by using a low‑work‑function metal electrode, boosting electron injection/extraction. The diode shows a good J–V response in the dark with a rectification ratio of 3 × 10³ at 1.0 V and an ideality factor of 4.2 (Al electrode), and under illumination the heterostructure achieves a power conversion efficiency of ≈0.37 % (Voc = 0.25 V, Jsc = 4.16 mA cm⁻²).

Abstract

In this article, we report the growth of zinc‐tin nitride (ZnSnN 2 ) thin films as a potential absorber for photovoltaic applications by fabricating a heterojunction of n‐ZnSnN 2 /p‐SnO. The performance of the heterojunction has been monitored through selective deposition of top electrode with different materials (Ni/Au or Al). The electron‐transfer process from the ZnSnN 2 layer to the cathode is facilitated by selecting metal electrode with relatively low work function, which also boosts up the electron injection or/and extraction. The diode exhibits a good J–V response in the dark with a rectification ratio of 3 × 10 3 at 1.0 V and an ideality factor of 4.2 in particular with Al as the top electrode. Under illumination, the heterostructure solar cell demonstrates a power conversion efficiency of ≈0.37% with an open circuit voltage of 0.25 V and a short circuit current density of 4.16 mA cm −2 . The prime strategies, on how to improve solar cell efficiency concerning band offsets and band alignment engineering are also discussed.