Realizing efficient organic/inorganic hybrid perovskite solar cells (PVSCs) with reduced toxic lead (Pb) content is important for developing sustainable clean photovoltaics. The vigorous progress made recently for tin (Sn)-and Pb/Sn-based PVSCs has drawn considerable attention because of their potential to reduce Pb content in perovskites. However, the inferior chemical stability of Sn to Pb element necessitates more sophisticated morphological and processing engineering of Sn-containing PVSCs in order to achieve high performance and stability. We have recently discovered that ascorbic acid (AA) can serve as a simple but effective additive to simultaneously enhance the performance and stability of Sn-containing PVSCs. It is revealed that AA as a commonly known antioxidant can retard the oxidation of Sn-containing precursor solution of perovskite while modulate its perovskite crystallization by forming intermediate complexes. This is evidenced by the prolonged photogenerated carrier lifetime (182.7 ns) of its derived MA 0.5 FA 0.5 Pb 0.5 Sn 0.5 I 3 film. As a result, a high PCE of 14.01% with improved stability can be realized in the binary metal PVSC with AA as additive, outperforming the value (12.18%) of the control device processed with the regular SnF 2 additive.
A low-temperature, solution-processable organic electron-transporting material (ETM) is successfully developed for efficient conventional n-i-p perovskite solar cells (PVSCs). This ETM can show a high efficiency over 17% on rigid device and 14.2% on flexible PVSC. To the best of our knowledge, this efficiency is among the highest values reported for flexible n-i-p PVSCs with negligible hysteresis thus far.
Solar photon‐to‐electron conversion with polymer solar cells (PSCs) has experienced rapid development in the recent few years. Even so, the exploration of molecules and devices in efficiently converting near‐infrared (NIR) photons into electrons remains critical, yet challenging. Herein presented is a family of near‐infrared nonfullerene acceptors (NIR NFAs, T1–T4) with fluorinated regioisomeric A–Aπ–D–Aπ–A backbones for constructing efficient single‐junction and tandem PSCs with photon response up to 1000 nm. It is found that the tuning of the regioisomeric bridge (Aπ) and fluoro (F)‐substituents on a molecular skeleton strongly influences the backbone conformation and conjugation, leading to the optimized optoelectronic and stable stacking of resultant NFAs, which eventually impacts the performance of derived PSCs. In PSCs, the proximal NFAs with varied F‐atoms (T1–T3) mostly outperform than that of distal NFA (T4). Notably, single‐junction PSC with PTB7‐Th:T2 blend can reach 10.87% power conversion efficiency (PCE), after implementing a solvent additive to improve blend morphology. Moreover, efficient tandem PSCs are fabricated through integrating such NIR cells with mediate bandgap nonfullerene‐based subcells, to achieve a PCE of 14.64%. The results reveal the structural design of organic semiconductor and device with improved photovoltaic performance.
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