Sputtered transparent electrodes for optoelectronic devices: Induced damage and mitigation strategies

Transparent electrodes and metal contacts deposited by magnetron sputtering find applications in numerous state-of-the-art optoelectronic devices, such as solar cells and light-emitting diodes. However, the deposition of such thin films may damage underlying sensitive device layers due to plasma emission and particle impact. Inserting a buffer layer to shield against such damage is a common mitigation approach. We start this review by describing how sputtered transparent top electrodes have become archetypal for a broad range of optoelectronic devices and then discuss the possible detrimental consequences of sputter damage on device performance. Next, we review common buffer-layer materials in view of their processing-property-performance relationship. Finally, we discuss strategies to eliminate the buffer-layer requirement by implementing alternative, soft-landing deposition techniques for top electrodes. Our review highlights the critical issue of sputter damage for optoelectronic devices, formulates mitigation strategies, and provides cross-field learnings that can lead to more efficient and reliable optoelectronic devices aimed for commercialization.