Electron acceptor degradation of organic solar cells is considered a main contributor to performance instability and a barrier for the commercialization of organic solar cells. Here, we selectively remove the electron acceptors on the surface of donor:acceptor blend films using a tape stripping technique. The near-edge X-ray absorption fine structure (NEXAFS) spectrum reveals that only 6% of the acceptor component is left on the blend film surface after the tape stripping, creating a polymer-rich surface. The optimized morphology avoids direct contact of electron acceptors with the oxygen and water molecules from the film surface. Moreover, the polymer-rich surface dramatically enhances the adhesion between the photoactive layer and the top metal electrode, which prevents delamination of the electrode. Our results finally demonstrate that the selective removal of electron acceptors near the top electrode facilitates the realization of highly durable organic solar cells that can even function under water without encapsulation.

Despite huge improvements in power conversion efficiencies of perovskite solar cells, the technology is still limited by fill factors at around 80%. Here, we report perovskite solar cells having exceptionally high fill factors of 85% and enhanced opencircuit voltage without sacrificing short-circuit current through a polymer-capped solventannealing process assisted by a hot air blower. During the solvent-annealing, the perovskite surface flattens and the perovskite grains agglomerate into micrometer-sized clusters having enlarged α-phase crystallites, while the δ-phase simultaneously disappears. The optimized structure reduces energetic disorder and trap-assisted recombination in the perovskite layer, resulting in an enhanced efficiency from 18.2% to 19.8% and improved device lifetime. Our results provide a pathway to increase the device efficiency and stability of perovskite solar cells, and have the potential to stimulate research on scalable polycrystal perovskite layer fabrication in optoelectronic devices.

Organic−inorganic hybrid perovskites have become one of the most promising thin-film solar cell materials owing to their remarkable photovoltaic properties. However, nonradiative recombination of carriers usually leads to inferior performance of perovskite (PVK) devices. Interface modification is one of the effective ways to improve separation of charges for perovskite solar cells (PSCs). Here, a small organic molecule of tetrafluorophthalonitrile (TFPN) is used to enhance the extraction and transportation of carriers at the PVK/hole transport layer (HTL) interface. The electron-rich C−F group effectively reduces the trap state density in the perovskite through chemical combination with the empty orbital of Pb 2+ or other electron traps on the PVK surface, resulting in enhanced interface contact between the PVK and HTL. Meanwhile, the CN group in TFPN also inactivates the defects caused by Pb 2+ . The Fermi level of the perovskite shifts by 0.15 eV to its valence band due to the strong electron acceptor nature of the F atom, indicating that positive dipoles and p-type doping emerge, which validly suppress the recombination of carriers for the PVK film. Therefore, the optimized PSC shows the highest power conversion efficiency (PCE) of 22.82% compared to 19.40% for the control one. The champion FF reaches up to 81.2% (PCE 21.44%) due to the effectively enhanced carrier separation. In addition, the unencapsulated device shows enhanced stability under air conditions.

Intrinsic defects are key factors that would affect the performance and stability of perovskite solar cells (PSCs). Herein, a sulfonamides additive, methyl 3‐sulfamoyl‐2‐thiophenecarboxylate (MSTC), is introduced into the PbI2 or FAI/MACl/MABr precursor solution, to prepare high‐quality PSCs with a two‐step method. After the addition of MSTC, all the devices show enhanced performance. With optimized MSTC incorporated into PSCs, the champion power conversion efficiency (PCE) of the PSCs is increased from 19.19% to 22.14%, and the stability is also improved. The MSTC‐FAI based device can still maintain 89% of its initial PCE compared to 68% of the control one after 15 days in ambient condition under relative humidity of 40–50% at room temperature in dark. Test results reveal that amido group in MSTC would coordinate with PbI2 or FAI through hydrogen bonding (NH···I), thus effectively enhancing the performance of devices. Nevertheless, the sulfonyl and carbonyl groups in MSTC would coordinate with the FAI precursor through chemical bond of COS and COC. And with the hydrogen bonding connection between MSTC and FAI, the inherent defects in the MSTC‐FAI based device are effectively suppressed, leading to the enhanced photovoltaic performance.

As a superstars of photovoltaic devices, organic–inorganic hybrid perovskite solar cells (PSCs) have garnered plenty of interest due to their superior character. However, many defects, such as carrier recombination, inferior stability, poor interface contact, have prevented their further development. Here, we demonstrate a novel approach of interface engineering to form a compact perovskite layer with decreased defects on SnO2 film by adding tris­(pentafluorophenyl)­boron (TPFPB) as an interfacial modification layer, which validly improves the interface performance and enhances the crystallinity of MAPbI3. Hence the planar MAPbI3 PSCs with TPFPB modification show fast charge transfer and low trap state density with an enhanced champion power conversion efficiency (PCE) from the original of 16.92% to 19.41%, as well as long-term stability with 80.7% of its initial PCE after 1000 h of aging in N2 atmosphere without encapsulation, while the pristine one only shows 68.9% of the original PCE. The results reveal that TPFPB can be used as an effective interface modification layer for high efficiency and stability PSCs, and it maybe also be used in other devices due to its superior interface modification for high quality crystallinity thin films.