Reducing Energetic Disorder for High-Efficiency Perovskite Solar Cells with Low Urbach Energy by in Situ NH₃...

The high disorder in perovskite materials leads to severe carrier non-radiative recombination, which directly determines the energy loss of photovoltaic devices. Currently, modulation of energetic disorder in perovskite solar cells and its correlation with open-circuit voltage losses (V_{OC, loss}) remain insufficiently understood. We regulated the perovskite crystallization process by in situ NH₃ generation, thereby enhancing the perovskite degree of energetic order. Density functional theory calculations reveal that lone-pair electrons on the N atom of the NH₃ molecule coordinate with Pb²⁺, increasing the defect formation energy of lead vacancies (V_Pb), Pb-on-I antisite (Pb_I), and I-on-Pb antisite (I_Pb) to 5.61, 0.37, and 4.09 eV, respectively. As a result, we obtained energetic ordered perovskite film with an Urbach energy of 23.7 meV. The champion device exhibited a reduced V_{OC, loss} by over than 50 mV and achieved an open-circuit voltage (V_OC) of 1.182 V with a power conversion efficiency (PCE) of 26.26%. Under the ISOS-D protocols, the device maintains over 95% of its initial efficiency after 1100 h of nitrogen storage and over 90% after 700 h at 65 °C. And the 5 × 5 cm² mini-modules achieved a PCE of 21.31%, representing state-of-the-art performance in perovskite photovoltaics.