Moving beyond the Shockley–Queisser limit: current bottlenecks and a new direction in solar energy conversion

Abstract

Third-generation solar cells offer a promising path to surpass the Shockley–Queisser efficiency limit through innovative materials and architectures. Concepts such as tandem solar cells, hot carrier extraction, carrier multiplication, intermediate band absorption, and photon upconversion each address specific energy loss mechanisms in conventional devices. This review provides a comprehensive overview of major third-generation strategies, outlining their principles, recent progress, and key limitations. Special emphasis is placed on the new conceptual lattice battery solar cell (LBSC), which is able to simultaneously overcome two major energy losses of hot phonon and sub-bandgap non-absorption in conventional solar cells, because LBSC integrates unique energy micro-recycle processes of hot phonon storage and subgap carrier upconversion within a single-junction architecture. Building on this, we introduce the concept of the lattice energy reservoir (LER), a dynamic energy retention mechanism proposed to operate within soft-lattice materials such as metal halide perovskites. LER offers a unified physical basis for LBSC operation by enabling temporal energy storage and reuse through strong lattice–carrier coupling. The LBSC framework highlights a new paradigm in solar energy conversion that leverages intrinsic material properties to overcome efficiency and stability challenges. This review thus aims to guide future efforts toward integrated, high-performance photovoltaic designs grounded in emerging lattice-physics insights.