Design Optimization of Bifacial Perovskite Minimodules for Improved Efficiency and Stability

Bifacial solar modules can produce more energy than monofacial ones, but efficient bifacial perovskite modules have not been demonstrated yet. Here we report bifacial perovskite minimodules with front efficiency comparable to that of the best opaque monofacial minimodules while gaining additional energy from albedo light. The addition of hydrophobic additive in bottom hole transport layer surprisingly protects the perovskite films from moisture damage during atomic layer deposition. Integrating silica nanoparticles with proper size and spacing in perovskite films recovers the absorption loss induced by the absence of reflective metal electrodes while maintains the charge collection properties of perovskites. The small-area single-junction bifacial cells have an equivalent stabilized efficiency of 26.4% at an albedo of 0.2. The bifacial solar minimodules show front efficiency of over 20% and bifaciality of 74.3%, and thus an equivalent efficiency of over 23% at an albedo of 0.2. The bifacial minimodule retained 97% of its initial efficiency after light soaking under one simulated sun for over 6000 hours at 60±5 °C.