Tin Halide Perovskite Solar Cells with Open-Circuit Voltages Approaching the Shockley–Queisser Limit

Abstract

The power conversion efficiency of tin-based halide perovskite solar cells is limited by large photovoltage losses arising from the significant energy-level offset between the perovskite and the conventional electron transport material, fullerene C 60 . The fullerene derivative indene-C 60 bisadduct (ICBA) is a promising alternative to mitigate this drawback, owing to its superior energy level matching with most tin-based perovskites. However, the less finely controlled energy disorder of the ICBA films leads to the extension of its band tails that limits the photovoltage of the resultant devices and reduces the power conversion efficiency. Herein, we fabricate ICBA films with improved morphology and electrical properties by optimizing the choice of solvent and the annealing temperature. Energy disorder in the ICBA films is substantially reduced, as evidenced by the 22 meV smaller width of the electronic density of states. The resulting solar cells show open-circuit voltages of up to 1.01 V, one of the highest values reported so far for tin-based devices. Combined with surface passivation, this strategy enabled solar cells with efficiencies of up to 11.57%. Our work highlights the importance of controlling the properties of the electron transport material toward the development of efficient lead-free perovskite solar cells and demonstrates the potential of solvent engineering for efficient device processing.

Tin‐Based Eco‐Friendly Perovskites for Sustainable Future

“…[ 139 ] Attempts to minimize the photovoltage losses arising between the perovskite and the C 60 , a well‐known electron transporting material, have led to the use of a fullerene derivative, indene‐C 60 bisadduct (ICBA). [ 140 ] Still, the energy mismatch arising from using ICBA drastically affects the PCE. To address this issue, the solvent and annealing temperature were optimized.…”

“…In addition to that, the annealing temperature was raised from 70 to 100 °C, which led to the PSCs displaying a V OC of 1.01 V, which approaches the famed Shockley–Queisser limit and is one of the highest reported so far. [ 140 ]…”

Evaporable Fullerene Indanones with Controlled Amorphous Morphology as Electron Transport Layers for Inverted Perovskite Solar Cells

“…Nonetheless, fullerene derivatives have inherent challenges. In the case of C 60 , which is most frequently used as the ETM in IPSCs, the imperfect alignment of its lowest unoccupied molecular orbital (LUMO) energy level with the conduction band (CB) of perovskite lowers the open-circuit voltage ( V OC ). − Moreover, the absence of functional groups in C 60 restricts its ability to effectively passivate charge traps, particularly at the interface, resulting in nonradiative voltage losses and poor device efficiency. Furthermore, the regular structure of C 60 promotes a tendency for self-aggregation, introducing instability into PSCs and compromising their long-term reliability .…”

An open-cage bis[60]fulleroid as an electron transport material for tin halide perovskite solar cells

“…S3, ESI †). These derivatives were fabricated by a mixed solvent 32 of chlorobenzene (CB)/CS 2 /1,2,4-trichlorobenzene (TCB) (10/5/1, v/v). They showed similar solubility in this solvent system.…”