Design optimization of bifacial perovskite minimodules for improved efficiency and stability

The efficiency and stability of bifacial perovskite solar modules are still relatively low. Here we report bifacial minimodules with front efficiency comparable to opaque monofacial counterparts, while gaining additional energy from albedo light. We add a hydrophobic additive to the hole transport layer to protect the perovskite films from moisture. We integrate silica nanoparticles with proper size and spacing in perovskite films to recover the absorption loss induced by the absence of reflective metal electrodes. The small-area single-junction bifacial perovskite cells have a power-generation density of 26.4 mW cm⁻² under 1 sun illumination and an albedo of 0.2. The bifacial minimodules show front efficiency of over 20% and bifaciality of 74.3% and thus a power-generation density of over 23 mW cm⁻² at an albedo of 0.2. The bifacial minimodule retains 97% of its initial efficiency after light soaking under 1 sun for over 6,000 hours at 60 ± 5 °C.