PCDTBT8‐Doped PffBT4T‐2OD‐Based Ternary Solar Cells with Enhanced Open‐Circuit Voltage, Fill Factor, and Charge Separation Efficiency

Abstract

The effect of a medium bandgap polymer doped into conventional binary heterojunction solar cells is investigated for ternary solar cells, which display different characteristics compared with traditional materials. First, the charge separation and recombination at the multi‐interface (double donors/single acceptor) and the charge transport between different phases are simulated to reveal the competition mechanism of electron transfer and insights into the merits and demerits of a hole transport layer with medium and narrow band gaps. Second, global modeling of performance for PCDTBT8‐doped PffBT4T‐2OD‐based ternary solar cells is established to evaluate the crucial parameters (open‐circuit voltage (V OC), short‐circuit current (J SC), fill factor (FF), and power conversion efficiency (PCE)) related to the experiment. The results demonstrate that the orbital energy levels, absorption peak, excited‐state, fluorescence lifetimes, and hole transportability are tunable upon the medium bandgap polymer doping process. The electron transfer process for the multi‐interface is enhanced by doping different bandgap polymers compared with a single interface, which contributes to the energy match and multistep jump mechanism. Ternary solar cells based on the doped polymer exhibit better V OC, FF, and PCE with weakened J SC. The theoretical calculations are in excellent agreement with experimental results. The global investigation of ternary solar cells can be used to interpret experiments and is viewed as an effective method for screening high‐performance solar cells.

Nonfused Dimethoxybenzene Electron Acceptors in Organic Solar Cells: From Molecular Design to Structure–Performance Relationship

“…In the processes of photocurrent generation, the interface plays a crucial role in determining the PCE of solar cell devices. Hence, the interfacial charge separation and recombination processes should be explored, as these processes at the interface will significantly affect the device’s efficiency. , According to the Marcus theory, the charge separation process corresponds to two key parameters: charge-separated transfer rate K int‑CS and charge recombination rate K int‑CR . When the K int‑CS is larger, excitons of the compound will facilitate dissociation, but the larger K int‑CR will restrict the charge separation process.…”

“…The methyl groups replaced the flanking groups of all molecules because many studies have shown that the change of the branched chain had almost no effect on electronic structures and properties. 33,34 The investigated monomers were optimized under the B3LYP 31,35 function and 6-311G(d,p) 31,36 basis set, which can create reliable geometries and precision for mediumsized acceptors. 31,32,37 One also calculated the energy levels and compared them with the experiment to prove the rationality of the selection method (see Table S1 for different functionals).…”

“…Based on Gaussian 09 software, the density functional theory (DFT) and time-dependent DFT (TD-DFT) were used to study all structures’ ground and excited states, respectively. The methyl groups replaced the flanking groups of all molecules because many studies have shown that the change of the branched chain had almost no effect on electronic structures and properties. , The investigated monomers were optimized under the B3LYP , function and 6-311G­(d,p) , basis set, which can create reliable geometries and precision for medium-sized acceptors. ,, One also calculated the energy levels and compared them with the experiment to prove the rationality of the selection method (see Table S1 for different functionals). All the calculated results have no imaginary frequency, which indicates that the energy of the original and designed molecular structures was minimum and stable.…”

Tailoring the D‐A‐D electron‐withdrawing core as hole transport materials towards boosting the transport performance of perovskite solar cells

“…An ideal molecule should have good stability that is an important parameter to assess the molecular function of HTMs. [40] The stability is generally evaluated by absolute hardness (η), which is calculated by [41,42] η…”

Intra-Molecular Electrical Field Regulated Nonlinear Catalyst Charge Transfer in the Organic Conjugated Molecular System

“…In perovskite solar cells (PSCs) [5][6][7][8], stability can be increased. In dye-sensitized solar cells (DSSCs) [9][10][11][12], the conjugate system is a good electron transport material [13][14][15]. Moreover, the widely used two-dimensional material graphene [16][17][18][19][20][21][22] also has a wide range of conjugated systems.…”