  Optical wireless communication (OWC) offers several complementary advantages
to radio-frequency wireless networks such as its massive available spectrum;
hence, it is widely anticipated that OWC will assume a pivotal role in the
forthcoming sixth generation wireless communication networks. Although
significant progress has been achieved in OWC over the past decades, the outage
induced by occasionally low received optical power continues to pose a key
limiting factor for its deployment. In this work, we discuss the potential role
of single-photon counting (SPC) receivers as a promising solution to overcome
this limitation. We present an overview of the applications of SPC-based OWC
systems in 6G networks, introduce their major performance-limiting factors,
propose a performance enhancement framework to tackle these issues, and
identify critical areas of open problems for future research.
