Advanced materials to overcome the challenges in the fabrication of stable and efficient perovskite solar cells by additive engineering: a review

Perovskite solar cells (PSCs) have attained record power conversion efficiency (PCE) of 25.6%. This is attributed to excellent tunable bandgap, high absorption coefficient, long diffusion length, and good charge carrier capacity. However, due to the nature of manufacturing processes and rapid crystal growth, there can be formation of surface defects. Various operating parameters cause defects that hamper the efficiency and operational stability of PSCs. This hurdle can be overcome by reducing defects in grain boundaries and simultaneously improving the perovskite crystallization and film formation process through incorporation of suitable additives/surface passivating strategies during manufacturing. Recent approaches to tailor the functional layers in PSC using different surface passivating agents toward achieving high performance solar cells with reduced hysteresis and improved stability are discussed in detail here. First, organic additives are discussed. Halide additives (organic) are discussed in depth first and then non-halide additives (organic) is also discussed. Inorganic halide additives are another important category of additives, which is also discussed in detail. Inorganic additives, which are nanomaterial-based additives are also discussed. Such additive or surface passivating agent-assisted methods used for interface optimization are summarized based on their overall impact on the improvement in power conversion efficiency as well as operational stability of PSCs. Potential boarder applications of this strategy include enhanced performance solar cells and it can prove be a state-of-the-art technique leading to enhanced efficiency and stability cells of commercial value. The present review is a readymade reference for the readers working or starting work in this field.