Solution-processable n-doped graphene-containing cathode interfacial material with a low work function demonstrates 16.52% power conversion efficiency in organic solar cells.
The mixtures of cations and anions used in hybrid halide perovskites for high-performance solar cells often undergo element and phase segregation, which limits device lifetime. We adapted Schelling’s model of segregation to study individual cation migration and found that the initial film inhomogeneity accelerates materials degradation. We fabricated perovskite films (FA
1–x
Cs
x
PbI
3
; where FA is formamidinium) through the addition of selenophene, which led to homogeneous cation distribution that retarded cation aggregation during materials processing and device operation. The resultant devices achieved enhanced efficiency and retained >91% of their initial efficiency after 3190 hours at the maximum power point under 1 sun illumination. We also observe prolonged operational lifetime in devices with initially homogeneous FACsPb(Br
0.13
I
0.87
)
3
absorbers.
Perovskite solar cells (PSCs) have become a promising candidate for the next‐generation photovoltaic technologies. As an essential element for high‐efficiency PSCs however, the heavy metal Pb is soluble in water, causing a serious threat to the environment and human health. Due to the weak ionic bonding in three‐dimensional (3D) perovskites, drastic structure decomposition occurs when immersing the perovskite film in water, which accelerates the Pb leakage. By introducing the chemically stable Dion‐Jacobson (DJ) 2D perovskite at the 3D perovskite surface, the film dissolution is significantly slowed down, which retards lead leakage. As a result, the Pb contamination is dramatically reduced under various extreme conditions. In addition, the PSCs device deliver a power conversion efficiency (PCE) of 23.6 % and retain over 95 % of their initial PCE after the maximum power point tracking for over 1100 h.
Three
alcohol-soluble nonconjugated polymers poly [p-(N,N-dimethylamino)styrene] (PSN),
poly[p-(N,N-dimethylamino)styrene]
oxide (PSO), and poly[p-(N,N-dimethylamino)styrene] mesylate (PSM) were devised and
synthesized for the application as cathode interlayers in the organic
solar cells (OSCs) based on PBDB-T:IT-M. All of the polymers contain
a highly polarized amino or ammonium group at the side chains, which
can improve electron collection ability of the cathode interfacial
layer of the OSCs. Both the amino and ammonium group with a negative
ion of oxygen allow PSN and PSO to possess intermolecular n-doping
effect with the IT-M acceptor at the interface. The understanding
of the relationship between the n-doping effect and the cathode interlayer
structures may offer additional insights to further develop novel
cathode interfacial materials for OSCs.
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