Novel Small Molecular Materials Based on Phenoxazine Core Unit for Efficient Bulk Heterojunction Organic Solar Cells and Perovskite Solar Cells

Abstract

Two novel Acceptor-Donor-Acceptor (A-D-A) structured small molecular (SM-) materials POZ2 and POZ3 using an electron-rich phenoxazine (POZ) unit as a core building block were designed and synthesized. Their unique characteristics, such as suitable energy levels, strong optical absorption in the visible region, high hole mobility, and high conductivity, prompted us to use them both as p-type donor materials (DMs) in SM-bulk heterojunction organic solar cells (BHJ OSCs) and as hole transport materials (HTMs) in CH 3 NH 3 PbI 3 -based perovskite solar cells (PSCs). The POZ2based devices yielded promising power conversion efficiencies (PCEs) of 7.44% and 12.8% in BHJ OSCs and PSCs, respectively, which were higher than the PCEs of 6.73% (BHJ-OSCs) and 11.5% (PSCs) obtained with the POZ3-based devices. Moreover, our results demonstrated that the POZ2 employing the electron-deficient benzothiazole (BTZ) as linker exhibited higher hole mobility and conductivity than that of the POZ3 using thiophene as linker, leading to better device performance both in BHJ-OSCs and PSCs. These results also provide guidance for the molecular design of high charge carrier mobility SM-materials for highly efficient BHJ OSCs and PSCs in the future.

Quantitative structure‐property relationship modeling of small organic molecules for solar cells applications

“…A, Training set: from yellow to blue, according to the experimental PCE (yellow, low; blue, high PCE); test set: red squares. B, Training set: gray; test set color‐scale according to scaffold similarity: compounds from Brabec et al (purple), compounds from Cheng et al (yellow), compounds from Sun et al (violet), compounds from Montcada et al (green), compounds from Löbert et al (pale blue), compounds from Montcada et al (pink), compounds from Gupta et al (orange)…”

“…Even if the final goal of using such statistical and molecular modeling approaches is to distinguish promising scaffolds from not promising ones, the ability to also differentiate among derivatives of the same scaffold is still a desirable feature. If we focus on the trend, it can be noted that nm_9 is the most underestimated candidate: This can be rationalized considering that both nm_9 and nm_10 contain a phenoxazine core unit, extensively used in DSSCs and organic light‐emitting diodes but poorly tested as donor material in SM‐BHJ OPV, thus not included in the training set. Molecule nm_10 is better estimated because of the presence of the benzothiadiazole linker, already known by the model because of molecules 1 and 2 of the training set, which contain a similar linker.…”

“…Such exceptional solid‐state properties are clearly not included in the proposed PhotD function. In addition, it can be noted that both nm_9 and nm_10 contain a phenoxazine core unit, which as already mentioned, it is known to have unique electronic and optical properties but not included in the training set used for building the PhotD funciton . Such considerations can be used to correct the definition of the PhotD function: This is exactly one of the advantages of using desirability functions.…”

High‐Efficiency Perovskite Solar Cells Employing a S,N‐Heteropentacene‐based D–A Hole‐Transport Material

“…[1][2][3][4][5][6] These three-dimensional perovskitesp ossess direct band gaps and strong light absorption in the visible region withl arge absorption coefficients, long exciton diffusion lengths,a nd high charge-carrier mobility.T he optimized morphology of the perovskite layer is the crucial factor for improved device performance, which strongly de-pends on the materials composition and processing conditions. [24][25][26][27][28] Yang andco-workers recently reported PCEs of 14.9 %i nd opant-free TiO 2 -based planarheterojunction CH 3 NH 3 PbI 3Àx Cl x perovskite devicesu sing an A-D-A (A = acceptor,D = donor) molecule comprising at erthiophene linker betweent he central benzodithiophene and the rhodanine acceptorm oieties. The mostf requently used HTM is the wide band gap 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamino)-9,9'spirobifluorene( spiro-MeOTAD) and has so far provent ob e the most effective HTM.…”

“…The mostf requently used HTM is the wide band gap 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamino)-9,9'spirobifluorene( spiro-MeOTAD) and has so far provent ob e the most effective HTM. [24][25][26][27][28] Yang andco-workers recently reported PCEs of 14.9 %i nd opant-free TiO 2 -based planarheterojunction CH 3 NH 3 PbI 3Àx Cl x perovskite devicesu sing an A-D-A (A = acceptor,D = donor) molecule comprising at erthiophene linker betweent he central benzodithiophene and the rhodanine acceptorm oieties. [15][16][17][18][19][20][21][22][23] In order to reduce the processing ando ptimization time and thereby overall device cost, several dopant-free low band gap HTMs were developed;d evices employing these HTMs yielded PCEs in the range of 10-15 %.…”