Quantum Chemical Design of D–π–A‐Type Donor Materials for Highly Efficient, Photostable, and Vacuum‐Processed Organic Solar Cells

Abstract

Organic photovoltaic (OPV) has become an interesting field for modern area of research due to ever green advantages like easy processing, tunable energy level, and low depletion of solar light. [1][2][3] It is also getting attention of researchers because it uses clean and neat unlimited solar light. [4,5] In past decade, the use of solar devices, i.e., silicon-based solar cells had many disadvantages as compared with modern area of OPVs due to high cost, low flexibility, and low working of active layers. [6,7] To date, highly efficient solar device (18.22% power conversion efficiency [PCE]) was developed by Liu et al. in lab using donor polymer D18 with Y6 acceptor fullerene-free acceptor. [8] Nowadays, the scientists are involved to explore the advantages of OPVs (as compared with silicon-based solar cells) and mechanisms that are used to amplify the PCE and to prolong the average life time of the device. [9][10][11] To explore the step for enhancing the average life time of OPV devices is very important because it is directly linked with commercial benefits. [12] In addition to these advantages, modern area researchers are busy to develop new active layer materials which enhance the PCEs of OPV devices. [13][14][15] On the basis of active layer materials, solar cells are divided into two main classes, one is polymer solar cells and the other is small-molecule-based organic solar cell (OSC). [16] Among these solar cells, small molecule-based OSCs (SMOSCs) are commonly used due to their increased efficiencies. [17,18] In SMOSCs, conjugate materials proved to be very successful because they enhance the pathway for traveling the charge density and also enhance the PCE. [19,20] In conjugated aromatic systems, thienothiophene derivatives are superb candidates for OPV due to planarity and high mobility of charges. [21] For large light-harvesting capability, certain parameters are considered like bathochromic shifting in absorption spectra, perfect π-skeleton of designed molecules, and high planarity. All these things are present in one isomer of TT named as thieno [3,2-b]thiophene. Due to various aforementioned advantages, thieno[3,2-b]thiophene is widely used in basic building block of small organic molecules that are used in OPV devices. [22,23] Many reports are present in literature in which thieno [3,2-b]thiophene was efficiently utilized like Zhang et al. [24] who used thieno [3,2-b]thiophene for OPV that not only enhances the mobility of charges but also proves long pathway for charge traveling with high PCE. Similarly, Kim et al. [25] and Shim et al. [26] reported vacuum-processed ternary organic solar cells (TOSCs) in which they made a blend by using donor materials with C 70 polymer that provided 8.02% PCE. Recently, Su et al. [27] reported D-π-A-type molecules using thieno [3,2-b]thiophene moiety in structural designing. The resultant molecules proved to be very beneficial as they provide high natural stability, planarity, and visible-light-harvesting. So, using efficient donor-π-acceptor skeleton, two modu...

Insights into end‐capped modifications effect on the photovoltaic and optoelectronic properties of S‐shaped fullerene‐free acceptor molecules: A density functional theory computational study for organic solar cells

“…End‐capped alteration as mentioned earlier is a successful strategy for designing new and efficient molecules for active layer. [ 28 ] In this report, end‐capped alteration of reference was done with different halogens, cyano, acetates, and thiophene rings for obtaining efficient molecules with reduced band gap and high charge mobility as shown in Figure 2.…”

“…Oscillating strength, light absorption range, and energy of exciton, with contribution of molecular orbitals are known as photovoltaic characteristics of the active layer molecules. [ 28 ] The high absorption values with good oscillating strength allow better photovoltaic potential.…”

Physicochemical insights into the rational designing of new acceptor molecules by donor bridge modifications for efficient solar cells: In silico chemistry

“…DFT and TD-DFT were employed for calculations of different photovoltaic and optoelectronic properties. [17][18][19][20][21] Different methods of theory with 6-31G(d,p) basis set were initially used for the selection of an appropriate functional/level for the rest of the calculations. After careful analysis, it is seen that method/functional MPW1PW91 with 6-31G (d,p) is the most reliable approach for all further analyses.…”

Impact of halogens on electronic and photovoltaic properties of organic semiconductors: A multiscale computational modeling

“…Recently, designing of efficient electron-acceptors for OSCs is a hot topic and large numbers of papers are published. [12][13][14] It is known fact that experimental work is very expensive [15][16][17] and majority of projects are funded from taxpayers money. No doubt, countless papers about computational (density functional theory) designing of materials for organic solar cells are reported.…”