N-Type Self-Doped Water/Alcohol-Soluble Conjugated Polymers with Tailored Energy Levels for High-Performance Polymer Solar Cells

Abstract

Naphthalene diimide (NDI) and perylene diimide (PDI) based polymeric semiconductors with high mobility have shown great promise as electron transport materials (ETMs) in applications such as highperformance polymer solar cells (PSCs) and other optoelectronic devices. However, these NDI and PDI semiconductors usually have limited adjustment of the lowest unoccupied molecular orbital (LUMO) energy levels, which hinders their further use in the organic electronic device. Here, by using various degrees of esterification instead of imide groups, three perylenetetracarboxylic acid derivatives based, self-doped, n-type water/ alcohol-soluble conjugated polymers (n-WSCPs) were developed, which can act as electron transport layers (ETLs) to produce high-performance PSCs. Owing to the distinct electron-deficient nature of the backbones, these n-WSCPs exhibited different optoelectronic properties. The relationships between doping effects, charge-transporting capabilities, interfacial modifications, and structures of n-WSCPs were systematically investigated. When these n-WSCPs were used as ETLs, highperformance PSCs with the efficiencies of near 9% and over 10% were achieved in the combinations of poly [[2,6-4,8-di(5ethylhexylthienyl) [3,4-b]thiophenediyl]] (PTB7-Th)/ [6,6]-phenyl-C 71 -butyric acid methyl ester (PC 71 BM) and poly (2,5-thiophene-alt-5,5′-(5,10-bis(4-(2-octyldodecyl)thiophen-2yl)naphtho [1,2-c:5,6-c′]bis ([1,2,5]thiadiazole)) (PNTT)/PC 71 BM, respectively. The device of PNTT/PC 71 BM still exhibited a high PCE of 9.37% when the thickness of ETL was increased to 50 nm. Our results demonstrate the identical importance of energy level alignment and electron transporting in the design of n-WSCPs used for thickness-insensitive ETLs in PSCs for large area practical applications.

Secondary Bonds Modifying Conjugate‐Blocked Linkages of Biomass‐Derived Lignin to Form Electron Transfer 3D Networks for Efficiency Exceeding 16% Nonfullerene Organic Solar Cells

“…Recently, some of them have been successfully demonstrated for some of NFAs‐OSCs and shows the improved PCEs. [ 14–16 ] However, as the shifted LUMO levels of different NFAs, it is inevitable to prepare many kinds of corresponding materials for electron transfer and collection. Generally, these electrolytes were synthesized with complicated procedure and cost‐consumption, which is contrary to the original intention of OSCs.…”

Concepts and principles of self-n-doping in perylene diimide chromophores for applications in biochemistry, energy harvesting, energy storage, and catalysis

“…A diverse range of self-n-doped materials have been reported as efficient ETLs and cathode interlayers in solar cells, some with benchmark performances. [22][23][24]31,[189][190][191][192][193][194] Numerous examples were recently reviewed elsewhere in excellent detail. 195 N-PDIs have been shown to increase the broadband absorption of active layers, improve ETL homogeneity, and enhance solvent orthogonality for improved processability of BHJs.…”

“…Self-n-doping amine and ammonium moieties have been incorporated as molecular components in a range of materials research fields, such as in low-dimensional perovskite-related hybrids, electron transporting materials in solar cells, thermoelectric composites, work function modifiers, and more. [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] While the chemical structures of the self-ndoped semiconductors seen across the literature are diverse, the most common derivatives are fullerenes, perylene diimides, naphthalene diimides, and fluorenes as shown in Figure 1. Each scaffold shown here exhibits a unique set of intrinsic physicochemical properties.…”

Non-conjugated polymers as thickness-insensitive electron transport materials in high-performance inverted organic solar cells

“…However, the thickness of most organic ETLs is usually less than 10 nm due to their low conductivity and electron mobility. Small molecular conjugated electrolytes [32][33][34][35] and conjugated polyelectrolytes (CPEs) [36][37][38][39] have been exploited for thickness-insensitive ETLs in traditional OSCs, but these ETLs are seldom used for thick ETLs in inverted OSCs because of their strong absorption in visible waveband. So far, only a few ndoping fullerene derivatives [40][41][42] and polyfluorene derivatives [43] have been developed as thickness-insensitive ETLs in inverted OSCs because doping via anion-induced electron transfer [40] is an available strategy to improve electron mobility and electrical conductivity of these organic ETLs.…”