Materials Design and Optimization for Next-Generation Solar Cell and Light-Emitting Technologies

Manzhos, Sergei; Chueh, Chu‐Chen; Giorgi, Giacomo; Kubo, Takaya; Saianand, Gopalan; Lüder, Johann; Sonar, Prashant; Ihara, Masataka

doi:10.1021/acs.jpclett.1c00714

Cited by 14 publications

(10 citation statements)

References 244 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Aggregated molecular assemblies have attracted considerable interest in many fields of scientific research and technological development, − especially for organic optoelectronic devices − such as light emitting diodes and solar cells. Their optoelectronic properties depend strongly on the aggregates’ structure and morphology, making an understanding of these properties essential to understanding and tuning device performance.…”

Section: Introductionmentioning

confidence: 99%

Structural Disorder as the Origin of Optical Properties and Spectral Dynamics in Squaraine Nano-Aggregates

et al. 2022

View full text Add to dashboard Cite

In contrast to regular J-and H-aggregates, thin film squaraine aggregates usually have broad absorption spectra containing both J-and H-like features, which are favorable for organic photovoltaics. Despite being successfully applied in organic photovoltaics for years, a clear interpretation of these optical properties by relating them to specific excited states and an underlying aggregate structure has not been made. In this work, by static and transient absorption spectroscopy on aggregated n-butyl anilino squaraines, we provide evidence that both the red-and blue-shifted peaks can be explained by assuming an ensemble of aggregates with intermolecular dipole−dipole resonance interactions and structural disorder deriving from the four different nearest neighbor alignments�in sharp contrast to previous association of the peaks with intermolecular charge-transfer interactions. In our model, the next-nearest neighbor dipole−dipole interactions may be negative or positive, which leads to the occurrence of J-and Hlike features in the absorption spectrum. Upon femtosecond pulse excitation of the aggregated sample, a transient absorption spectrum deviating from the absorbance spectrum emerges. The deviation finds its origin in the excitation of two-exciton states by the probe pulse. The lifetime of the exciton is confirmed by the band integral dynamics, featuring a single-exponential decay with a lifetime of 205 ps. Our results disclose the aggregated structure and the origin of red-and blue-shifted peaks and explain the absence of photoluminescence in squaraine thin films. Our findings underline the important role of structural disorder of molecular aggregates for photovoltaic applications.

show abstract

Section: Introductionmentioning

confidence: 99%

Structural Disorder as the Origin of Optical Properties and Spectral Dynamics in Squaraine Nano-Aggregates

et al. 2022

View full text Add to dashboard Cite

show abstract

“…The MA model is used in organic disordered semiconductors, polycrystalline and amorphous semiconductors, and many CQD-materials. We use the common MA model for CQD-materials [ 16 , 35 , 75 ].…”

Section: Methodsmentioning

confidence: 99%

“…This aims at selecting the shell of surface ligands which assists in [ 6 ]: (a) Stabilizing the NC in different organic solvents; (b) Passivating the defects on the NC surface that act as non-radiative recombination centers [ 8 , 9 , 10 , 11 , 12 ], reducing the traps density [ 7 ] and increasing the carrier lifetimes in solar cells; (c) Exchanging ligands for others to control the inter-dot distance (and thus the coupling between dots); (d) Exchanging long ligands for shorter ones that work as electronic bridges between NCs to increase carrier extraction [ 13 , 14 , 15 ]. (e) Establishing their p -type or n -type nature [ 16 ]; (f) Controlling the energy of the band edges in conventional II-VI and IV-VI CQDs [ 17 , 18 , 19 ].…”

Section: Introductionmentioning

confidence: 99%

Carrier Transport in Colloidal Quantum Dot Intermediate Band Solar Cell Materials Using Network Science

Cuadra

Salcedo‐Sanz

Borge

2023

IJMS

View full text Add to dashboard Cite

Colloidal quantum dots (CQDs) have been proposed to obtain intermediate band (IB) materials. The IB solar cell can absorb sub-band-gap photons via an isolated IB within the gap, generating extra electron-hole pairs that increase the current without degrading the voltage, as has been demonstrated experimentally for real cells. In this paper, we model the electron hopping transport (HT) as a network embedded in space and energy so that a node represents the first excited electron state localized in a CQD while a link encodes the Miller–Abrahams (MA) hopping rate for the electron to hop from one node (=state) to another, forming an “electron-HT network”. Similarly, we model the hole-HT system as a network so that a node encodes the first hole state localized in a CQD while a link represents the MA hopping rate for the hole to hop between nodes, leading to a “hole-HT network”. The associated network Laplacian matrices allow for studying carrier dynamics in both networks. Our simulations suggest that reducing both the carrier effective mass in the ligand and the inter-dot distance increases HT efficiency. We have found a design constraint: It is necessary for the average barrier height to be larger than the energetic disorder to not degrade intra-band absorption.

show abstract

“…Organic semiconductors (OSCs) attract a great deal of attention owing to its immediate and increasingly demanded applications in organic photovoltaics (OPVs), − organic light-emitting diodes, , molecular electronics, biotechnology, and quantum teleportation . For example, the recently discovered OPV solar cells with non-fullerene acceptors have reached a new record with a power conversion efficiency of 19.6% .…”

Section: Introductionmentioning

confidence: 99%

Charge-Transfer Landscape Manifesting the Structure–Rate Relationship in the Condensed Phase Via Machine Learning

Brian

Sun

2021

J. Phys. Chem. B

View full text Add to dashboard Cite

In this work, we develop a machine learning (ML) strategy to map the molecular structure to condensed phase charge-transfer (CT) properties including CT rate constants, energy levels, electronic couplings, energy gaps, reorganization energies, and reaction free energies which are called CT fingerprints. The CT fingerprints of selected landmark structures covering the conformation space of an organic photovoltaic molecule dissolved in an explicit solvent are computed and used to train ML models using kernel ridge regression. The ML models show high predictive power with R 2 > 0.97 and both mean absolute error and root-mean-square error within chemical accuracy. The CT landscape for millions of molecular dynamics sampled structures is thus constructed, which allows for instant prediction of CT rate properties, given any conformation of the molecule. We demonstrate some immediate utilities of the CT landscape such as calculating the ensemble-averaged CT rate constant and interpreting the effects of molecular structural features on the CT rate. The unprecedented CT landscape will be useful for investigating real-time CT dynamics in nanoscale-and mesoscale-condensed phase systems and for the optimal fabrication design for homogeneous and heterogeneous optoelectronic devices.

show abstract

Materials Design and Optimization for Next-Generation Solar Cell and Light-Emitting Technologies

Cited by 14 publications

References 244 publications

Structural Disorder as the Origin of Optical Properties and Spectral Dynamics in Squaraine Nano-Aggregates

Structural Disorder as the Origin of Optical Properties and Spectral Dynamics in Squaraine Nano-Aggregates

Carrier Transport in Colloidal Quantum Dot Intermediate Band Solar Cell Materials Using Network Science

Charge-Transfer Landscape Manifesting the Structure–Rate Relationship in the Condensed Phase Via Machine Learning

Contact Info

Product

Resources

About