Identifying lead leakage and stability as major challenges for the commercialization of perovskite solar cells (PSCs), researchers from Chongqing University and Huazhong University of Science and Technology have developed a polymerization method to achieve highly stable and environmentally friendly high-performance PSCs.
Device structure diagram of the PSCs and corresponding cross-sectional SEM image. Image from: Science Advances
Through the addition of the small organic molecule N,N′-bis(acryloyl)cystamine (BAC) to the perovskite precursor solution, the terminal alkenes of BAC enable the construction of polymer BAC (PBAC) at the perovskite grain boundaries (GBs) during the annealing process of the perovskite films. PBAC not only overcomes the limitations of organic small molecules but also interacts with perovskites through its numerous functional groups and multiple reactive sites. This interaction effectively passivates deep-level defects, suppressing nonradiative carrier recombination.
Furthermore, the PBAC-modified film demonstrated enhanced water resistance, effectively suppressing the migration of I− and contributing to enhanced operational stability under extreme conditions.
The PSCs with PBAC achieved an impressive PCE of 25.53% (0.1 cm2) (certified at 25.24%) and 24.03% at a larger area (1.0 cm2).
Simultaneously, the unencapsulated devices maintained a value of more than 96% after continuous operation for 1500 hours under simulated AM 1.5 illumination.
Furthermore, under damp heat conditions [85°C and 85% relative humidity (RH)], the encapsulated device retained more than 80% of its initial PCE during 2000 continuous hours of operation.
Owing to the encapsulation of the polymer around the GBs and its anchoring ability to lead, the PBAC-modified PSCs exhibited a reduction in lead leakage. This research holds the promise of providing strategies for exploring high-performance and environmentally friendly PSCs.
