Accelerated computational discovery of high-performance materials for organic photovoltaics by means of cheminformatics

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1 Electronic upplementary Material (EI) for Energy & Environmental cience This journal is The Royal ociety of Chemistry 2011 Accelerated computational discovery of high-performance materials for organic photovoltaics by means of cheminformatics Roberto livares-amaya a, Carlos Amador-Bedolla a,b, Johannes Hachmann a, ule Atahan-Evrenk a, Roel. ánchez-carrera a, Leslie Vogt a and Alán Aspuru-Guzik a a Department of Chemistry and Chemical Biology, Harvard University, 12 xford t, Cambridge, MA 02138, UA b Facultad de Química, Universidad acional Autónoma de México, México, DF 04510, México aspuru@chemistry.harvard.edu July 1, Molecular Library Generation In cheme 1, we show the set of building blocks. These are used to generate the molecular library. Further details of the molecular library generation will be detailed in a separate publication. 1 2 Descriptors We selected a subset of descriptors available through ChemAxon. The subset selected is shown in Table 1. These descriptors were coded in a program and applied to our huge set of molecules. It should be noted that many descriptors are calculated for each atom of the molecule. In these cases we selected the lowest, the highest and the average value to be used in the calibration and in the prediction. 3 Calibration molecules We selected a set of 50 molecules which have been studied experimentally and results are available. We built molecular formulae from the original papers. For these calculations, aliphatic chains were stripped from the molecular formula. The set of molecules with efficiency parameters measured experimentally, thus used in this study, is shown in Fig. 1 and Fig election of descriptors and results for the calibration molecules Fig. 3, Fig. 4 and Fig. 5 show plots of V oc versus each one of the 33 descriptors, none of them showing an obvious correlation. We used R to perform a multiple linear regression. As could have been expected, 50 experimental data with 33 descriptors make for a very good fit with R-squared of ome of the descriptors are not statistically significant, so we removed the less significant descriptors and ended up with Present Address: Robert Bosch LLC Research and Technology Center, 1 Cambridge Center, Cambridge, MA,

2 Electronic upplementary Material (EI) for Energy & Environmental cience This journal is The Royal ociety of Chemistry 2011 Table 1 The set of descriptors calculated using ChemAxon. 1. Molecular mass 2. logp partition constant octanol/water 3. Ring count 4. Hydrogen bond acceptor atom count in molecule 5. Hydrogen bond donor atom count in molecule 6. Rotatable bond count 7. Molecular polarizability 8. Refractivity 9. van der Waals surface area 10. van der Waals volume 11. Water accesible area calculation (AA) 12. Water accesible area calculation of all atoms with positive partial charge (AA+) 13. Water accesible area calculation of all atoms with negative partial charge (AA-) 14. Water accesible area calculation of all hydrophobic ( q i < 0.125) atoms (AA H) 15. Water accesible area calculation of all polar ( q i >= 0.125) atoms (AA P) 16. Electrophilic localization energy (lowest) 17. Electrophilic localization energy (highest) 18. Electrophilic localization energy (average) 19. Partial charge calculation (lowest) 20. Partial charge calculation (highest) 21. Partial charge calculation (average) 22. Electron density (lowest) 23. Electron density (highest) 24. Electron density (average) 25. teric hindrance (lowest) 26. teric hindrance (highest) 27. teric hindrance (average) 28. rbital electronegativity (sigma) (lowest) 29. rbital electronegativity (sigma) (highest) 30. rbital electronegativity (sigma) (average) 31. rbital electronegativity (pi) (lowest) 32. rbital electronegativity (pi) (highest) 33. rbital electronegativity (pi) (average) a fitting from 20 descriptors (with R-squared of ) all of them significant. Table 2 show results of the fitting. ext, we used the same technique for J sc. Table 3 show results of the fitting. In this case, 18 significant descriptors fit the experimental values with R-squared of Table 4 show results of the fitting of PCE. In this case, 15 significant descriptors fit the experimental values with R-squared of Table 5 show results of the fitting of FF. In this case, 20 significant descriptors fit the experimental values with R-squared of ; not all of them are significant but one has to go to only 12 descriptors to get them all significant and then R-squared drops to This is interpreted as meaning that the fitting for FF is not credible at all, as it may be expected for this morphology based experimental parameter. Table 6 show results of the fitting of the product V oc J sc. The fitting is good with R-squared of and all 20 descriptors are significant. A common test of the calibration of the training set to the descriptors is the leave 1/3 out technique. The whole set of calibration molecules is randomly divided in three subsets: A (17 molecules in this case), B (17 molecules), and C (16 molecules). For V oc, the set of 20 descriptors previously selected is used to fit 2

3 Electronic upplementary Material (EI) for Energy & Environmental cience This journal is The Royal ociety of Chemistry 2011 Table 2 Results for the fitting of V oc to 20 descriptors Estimate td. Error t value Pr(> t ) (Intercept) e-09 *** logp e-09 *** RingCount e-08 *** AcceptorCount e-08 *** RotBondCount e-11 *** Refractivity *** VdWArea e-08 *** VdWVolume e-06 *** AA ** AAH * ElecLocEn(lo) * PartialCh(lo) *** PartialCh(hi) e-06 *** PartialCh(avg) e-08 *** ElecDen(lo) ** ElecDen(avg) e-11 *** terichind(hi) e-06 *** σeleceg(lo) ** σeleceg(hi) * σeleceg(avg) e-07 *** πeleceg(hi) e-07 *** ignif. codes: 0 *** ** 0.01 * Residual standard error: on 29 degrees of freedom (8 observations deleted due to missingness) Multiple R-squared: , Adjusted R-squared: F-statistic: on 20 and 29 DF, p-value: 4.09e-13 separately to the subsets AB (34 molecules), AC (33 molecules) and BC (33 molecules). The coefficients thus obtained are used to predict J sc for the set not used in the fitting (C for AB, for instance). Results are shown in Fig. 6. As can be seen, the prediction of excluded molecules is consistent. We performed the same analysis for J sc results are shown in Fig. 7 and for the product V oc J sc results shown in Fig. 8. 3

4 Electronic upplementary Material (EI) for Energy & Environmental cience This journal is The Royal ociety of Chemistry 2011 Table 3 Results for the fitting of J sc to 18 descriptors Estimate td. Error t value Pr(> t ) (Intercept) e-08 *** logp ** AcceptorCount *** DonorCount *** RotBondCount e-08 *** MolPolarizability ** AA *** AA *** AAH *** AAP *** ElecLocEn(lo) e-08 *** ElecLocEn(avg) e-07 *** ElecDen(lo) *** terichind(hi) e-06 *** σeleceg(lo) *** σeleceg(hi) * σeleceg(avg) e-08 *** πeleceg(hi) * πeleceg(avg) e-07 *** ignif. codes: 0 *** ** 0.01 * Residual standard error: on 31 degrees of freedom (8 observations deleted due to missingness) Multiple R-squared: , Adjusted R-squared: F-statistic: on 18 and 31 DF, p-value: 1.016e-10 References [1] In Preparation,

5 Electronic upplementary Material (EI) for Energy & Environmental cience This journal is The Royal ociety of Chemistry 2011 Table 4 Results for the fitting of %PCE to 15 descriptors Estimate td. Error t value Pr(> t ) (Intercept) e-06 *** RotBondCount e-05 *** Refractivity ** VdWArea ** AA e-05 *** AA e-05 *** AAH e-05 *** AAP e-05 *** ElecLocEn(hi) ** PartCharge(avg) ElecDen(lo) *** terichind(lo) ** σeleceg(hi) * σeleceg(avg) e-09 *** πeleceg(hi) *** πeleceg(avg) * ignif. codes: 0 *** ** 0.01 * Residual standard error: on 33 degrees of freedom (9 observations deleted due to missingness) Multiple R-squared: , Adjusted R-squared: F-statistic: on 15 and 33 DF, p-value: 3.784e-09 5

6 Electronic upplementary Material (EI) for Energy & Environmental cience This journal is The Royal ociety of Chemistry 2011 e e H H 2 i H 2 i H H H 2 i cheme 1 The thirty basic heterocyclic units used in this study are shown with their Mg chemical handles at the 2,5- or para- position of the five-membered and six-membered ring, respectively. 6

7 i e e Fig. 1 First set of the fifty experimentally characterized molecules (shown here without aliphatic side chains). nce stripped of the aliphatic tails, several molecules are equivalent (6 and 8; 3, 16 and 18; and 48 and 50), but all are retained in the training set. 7 Electronic upplementary Material (EI) for Energy & Environmental cience This journal is The Royal ociety of Chemistry 2011

8 i i i i i i i i Fig. 2 econd set of the fifty experimentally characterized molecules (shown here without aliphatic side chains). nce stripped of the aliphatic tails, several molecules are equivalent (6 and 8; 3, 16 and 18; and 48 and 50), but all are retained in the training set. 8 Electronic upplementary Material (EI) for Energy & Environmental cience This journal is The Royal ociety of Chemistry 2011

9 Electronic upplementary Material (EI) for Energy & Environmental cience This journal is The Royal ociety of Chemistry 2011 Table 5 Results for the fitting of FF to 20 descriptors. ote that not all of them are significant. Estimate td. Error t value Pr(> t ) (Intercept) MolecMass RingCount ** DonorCount * RotBondCount ** MolPolarizability ** VdWVolume AA * AA * AA * AAP ElecLocEn(lo) ** ElecLocEn(hi) ** ElecLocEn(avg) ** PartialCharge(lo) PartialCharge(avg) ElecDen(hi) ** ElecDen(avg) ** σeleceg(hi) * πeleceg(lo) πeleceg(hi) ignif. codes: 0 *** ** 0.01 * Residual standard error: on 28 degrees of freedom (9 observations deleted due to missingness) Multiple R-squared: , Adjusted R-squared: F-statistic: on 20 and 28 DF, p-value:

10 Electronic upplementary Material (EI) for Energy & Environmental cience This journal is The Royal ociety of Chemistry 2011 Table 6 Results for the fitting of V oc J sc to 20 descriptors Estimate td. Error t value Pr(> t ) (Intercept) e-06 *** MolMass * logp ** AcceptorCount ** DonorCount * RotBondCount e-07 *** Refractivity *** AA ** AA ** AA ** AAP ** ElecLocEn(lo) e-05 *** ElecLocEn(avg) e-06 *** PartCharge(hi) ** ElecDen(lo) *** ElecDen(avg) terichind(hi) *** σeleceg(lo) *** σeleceg(avg) e-06 *** πeleceg(hi) *** πeleceg(avg) e-05 *** ignif. codes: 0 *** ** 0.01 * Residual standard error: on 29 degrees of freedom (8 observations deleted due to missingness) Multiple R-squared: , Adjusted R-squared: F-statistic: on 20 and 29 DF, p-value: 1.427e-08 10

11 value V Mass logp RingCount AccepCount DonorCount RotBondCoun Polariz Refractiv vdwurf vdwvol AA Fig. 3 Experimental values of V oc versus a set of 33 descriptors obtained from ChemAxon for the set of 50 calibration molecules stripped of their aliphatic tails. 11 Electronic upplementary Material (EI) for Energy & Environmental cience This journal is The Royal ociety of Chemistry 2011

12 value V AAplus AAminus AAH AAP ElecLocEn ElecLocEn ElecLocEn PartCh PartCh PartCh ElecDen1 Fig. 4 Experimental values of V oc versus a set of 33 descriptors obtained from ChemAxon for the set of 50 calibration molecules stripped of their aliphatic tails. 12 Electronic upplementary Material (EI) for Energy & Environmental cience This journal is The Royal ociety of Chemistry 2011

13 value V ElecDen ElecDen terichind terichind terichind rbeleci rbeleci rbeleci rbelecpi rbelecpi rbelecpi3 Fig. 5 Experimental values of V oc versus a set of 33 descriptors obtained from ChemAxon for the set of 50 calibration molecules stripped of their aliphatic tails. 13 Electronic upplementary Material (EI) for Energy & Environmental cience This journal is The Royal ociety of Chemistry 2011

14 Electronic upplementary Material (EI) for Energy & Environmental cience This journal is The Royal ociety of Chemistry 2011 Leave 1/3 out validation! experimental! predicted from ABC! predicted from AB! predicted from AC! predicted from BC! Fig. 6 Results of the leave 1/3 out correlation test for V oc. 14

15 Electronic upplementary Material (EI) for Energy & Environmental cience This journal is The Royal ociety of Chemistry 2011 Leave 1/3 out validation! experimental! predicted from ABC! predicted from AB! predicted from AC! predicted from BC! Fig. 7 Results of the leave 1/3 out correlation test for J sc. 15

16 Electronic upplementary Material (EI) for Energy & Environmental cience This journal is The Royal ociety of Chemistry 2011 Leave 1/3 out validation! experimental! predicted from ABC! predicted from AB! predicted from AC! predicted from BC! Fig. 8 Results of the leave 1/3 out correlation test for V oc J sc. 16

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