It is crucial to make perovskite solar cells sustainable and have a stable operation under natural light soaking before they become commercially acceptable. Herein, a small amount of the small molecule bathophenanthroline (Bphen) is introduced into [6,6]‐phenyl‐C61‐butyric acid methyl ester and it is found that Bphen can stabilize the C60‐cage well through formation of much more thermodynamically stable charge‐transfer complexes. Such a strengthened complex is used as an interlayer at the in‐light perovskite/SnO2 side to achieve a champion device with efficiency of 23.09% (certified 22.85%). Most importantly, the stability of the resulting devices can be close to meeting the requirements of the International Electrotechnical Commission 61215 standard under simulated UV preconditioning and light‐soaking testing. They can retain over 95% and 92% of their initial efficiencies after 1100 h UV irradiation and 1000 h continuous illumination of maximum power point tracking at 60 °C, respectively.

Ion migration, an intrinsic property that cannot be suppressed by device encapsulation, is of great importance to the long-term stability of perovskite solar cells. Herein, we synthesize a polyethylene glycol-modified fullerene (PCBHGE) and then incorporate it into perovskite absorber layers. It is found that PCBHGE can stabilize [PbI 6 ] 4− octahedral frameworks by forming Lewis acid−base pairs. Decoupling the efficient defect passivation of the fullerene core, ion migration is suppressed significantly in the as-fabricated devices. As a result, our state-of-the-art device demonstrates a highest efficiency of 23.19%. Most importantly, the device with PCBHGE can retain 87% of its maximum efficiency after 206 days. Tracked at the maximum power point under a continuous bias, the device efficiency hardly decreases in the first 212 h with a UV filter and can retain 80% of its initial efficiency after the next 600 h under full spectrum illumination including UV light.

High‐performance perovskite solar cells (PVSCs) with low energy consumption and green processing are highly desired, but constrained by the difficulty in morphology control and the poor understanding on morphology evolution mechanisms. To address this issue, here we studied the effect of antisolvents on the perovskite film formation. We found that both the antisolvents and the perovskite composition affect the perovskite film morphology greatly via influencing the intermediate phase, and different perovskite compositions require different antisolvents to reach the optimal morphology. This provides the opportunity to achieve high‐performance PVSCs with green antisolvent, that is, isopropanol (iPA) by changing the perovskite compositions, and leads to a power conversion efficiency (PCE) of 21.50% for PVSCs based on MA0.6FA0.4PbI3. Further, we fabricated “fully green” PVSCs with all layers prepared by green solvents, and the optimal PCE can reach 19%, which represents the highest among PVSCs with full‐green processing. This work provides insight into the perovskite morphology evolution and paves the way toward “green” processing PVSCs.

Wide‐bandgap perovskite solar cells (PSCs) with an optimal bandgap between 1.7 and 1.8 eV are critical to realize highly efficient and cost‐competitive silicon tandem solar cells (TSCs). However, such wide‐bandgap PSCs easily suffer from phase segregation, leading to performance degradation under operation. Here, it is evident that ammonium diethyldithiocarbamate (ADDC) can reduce the detrimental I2 back to I− in precursor solution, thereby reducing the density of deep level traps in perovskite films. The resultant perovskite film exhibits great phase stability under continuous illumination and 30–60% relative humidity conditions. Due to the suppression of defect proliferation and ion migration, the PSCs deliver great operation stability which retain over 90% of the initial power conversion efficiency (PCE) after 500 h maximum power point tracking. Finally, a highly efficient semitransparent PSC with a tailored bandgap of 1.77 eV, achieving a PCE approaching 18.6% with a groundbreaking open‐circuit voltage (VOC) of 1.24 V enabled by ADDC additive in perovskite films is demonstrated. Integrated with a bottom silicon solar cell, a four‐terminal (4T) TSC with a PCE of 30.24% is achieved, which is one of the highest efficiencies in 4T perovskite/silicon TSCs.

Wide-bandgap (WBG) perovskite solar cells (PSCs) with high performance and stability are in considerable demand in the photovoltaic market to boost tandem solar cell e ciencies. Perovskite bandgap broadening results in a high barrier for enhancing the e ciency of the PSCs and causes phase segregation in perovskite. In this study, we show that the residual strain is the key factor affecting the WBG perovskite device e ciency and stability. The DMSO addition not only helps lead halide to with opening the vertical layer spacing to form (CsI)0.08(PbI1.4Br0.6) and (CsI0.125Br0.875)0.08(PbI1.2Br0.8) intermediate phases, but also provide more nucleation sites to eliminate lattice mismatch with FAX (X = I, Br or Cl) or MAX, which dominates the strain effects on the WBG perovskite growth in a sequential deposition. By minimizing the strain, 1.67-and 1.77-eV nip devices with record e ciencies of 22.28% and 20.45%, respectively, can be achieved. The greatly enhanced suppression of phase segregation enables the device with retained 90% -95% of initial e ciency over 4000 h of damp stability and 80% -90% of initial e ciency over 700 h of maximum-power-point output stability under full-spectrum light without encapsulation. Besides, the 1.67-eV pin devices can achieve a competitive 22.3% e ciency while achieving considerable damp-heat, pre-ultraviolet (pre-UV) aging, and MPP tracking stability as per the tests conducted according to IEC 61215. The nal e ciency for the perovskite/Si tandem is more than 28.3 %, which matches the top e ciencies reported to date.