supplementary information: free charge photogeneration in
TRANSCRIPT
1
Supplementary Information: Free Charge 1
Photogeneration in a Single Component High Photovoltaic 2
Efficiency Organic Semiconductor 3
Michael B. Pricea,b,1,*, Paul A. Humea,b,1,*, Aleksandra Ilinaa,b, Isabella Wagnera,b, Ronnie R. 4 Tamminga,b, Karen E. Thorna,b, Wanting Jiaoc, Alison Campbelld, Patrick J. Conaghand, Girish 5 Lakhwanid, Nathaniel J.L.K. Davisa,b, Yifan Wange,f, Peiyao Xuee, Heng Lue, Kai Chena,b, 6 Xiaowei Zhane, Justin M. Hodgkissa,b,* 7
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a School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington, New 9 Zealand 10
b MacDiarmid Institute for Advanced Materials and Nanotechnology, New Zealand. 11
c Ferrier Research Institute, Victoria University of Wellington, Wellington, New Zealand 12
dARC Centre of Excellence in Exciton Science, School of Chemistry, University of Sydney, NSW 13 2006, Australia 14
e School of Materials Science and Engineering, Peking University, Beijing 100871, China. 15
f College of Materials Science and Engineering, Qingdao University, Qingdao 266071, China 16
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* Correspondence should be sent to J.M.H. ([email protected]), P.A.H. 18 ([email protected]), and M.B.P. ([email protected]) 19
1 Authors contributed equally to this work 20
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Table of contents 34
35
Figure S1. Chemical structures, names, and abbreviations for all materials discussed in the 36
main manuscript. ........................................................................................................................ 3 37
Figure S2. Intensity-dependent photoluminescence quantum efficiency on multiple Y6 thin 38
films (normalised). ..................................................................................................................... 4 39
Figure S3. TA spectra and kinetics of Y6 in solid solution of polystyrene versus neat film. ... 5 40
Figure S4. Fluence dependent exciton kinetics from transient absorption. ............................... 5 41
Figure S5. Excitation energy-dependent exciton kinetics from transient absorption. ............... 6 42
Figure S6. Evidence of long-lived triplets in Y6 neat thin film transient absorption. ............... 6 43
Figure S7. Optically-pumped time-resolved terahertz absorption kinetic of neat Y6, compared 44
to transient absorption kinetic decays of excitons and charges. ................................................ 7 45
Kinetic models of Singlet, CT-state, and Free Charge interconversion .................................... 8 46
Table S1. Rate constants based on Singlet-CT state-free charge model from transient 47
absorption and PLQE measurements. ........................................................................................ 9 48
Figure S8. Variance of Model 1 kinetics compared to measured TA kinetics for simulated 49
PLQE’s that include a rise in value with fluence. .................................................................... 10 50
Table S2. Rate constants based on singlet-free charge model from transient absorption and 51
PLQE measurements. ............................................................................................................... 11 52
Figure S9. Model 2, with no CT states, fitted to experimental TA, PLQE, and compared to 53
the Saha equation. .................................................................................................................... 12 54
Figure S10. Variance of Model 2 kinetics compared to measured TA kinetics for simulated 55
PLQE’s that include a rise in value with fluence. .................................................................... 13 56
Photon Reabsorption in thin films ........................................................................................... 14 57
Figure S11. Simulated PLQE of Y6 with and without the effect of photon recycling. ........... 14 58
Figure S12. Current density-voltage (J-V) curves for single component Y6 devices with 59
different hole extraction layers. ............................................................................................... 15 60
Figure S13. Intensity dependence of short-circuit current density in a low range – from 0.024 61
to 0.1 suns. ............................................................................................................................... 15 62
Figure S14. J-V curves for Y6 devices with very low donor content of PTB7-Th. ................ 16 63
Figure S15. Exciton, electron, and hole dynamics in a 1:1.2 PTB7-Th:Y6 blend measured by 64
transient absorption. ................................................................................................................. 16 65
Figure S16. Exciton and charge kinetics for neat Y6 compared to Y6 blended with 0.2 weight 66
fraction PCBM. ........................................................................................................................ 17 67
Figure S17. Energy levels and electronic couplings for localized exciton and CT states. ...... 18 68
Figure S18. Ionization energy (IE) and electron affinity (EA) calculated using long-range 69
polarizable embedding of charges in a model thin film. .......................................................... 18 70
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3
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Figure S1. Chemical structures, names, and abbreviations for all materials discussed in 73 the main manuscript. a) 2,20-((2Z,20Z)-((12,13-bis(2-ethylhexyl)-3,9-diundecyl-12,13-74 dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2,"30':4',50]thieno[20,30:4,5]pyrrolo[3,2-75 g]thieno[20,30:4,5]thieno-[3,2-b]indole-2,10-diyl)bis(me-thanylylidene))bis(5,6-difluoro-3-76
oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (Y6)1, b) Poly[(2,6-(4,8-bis(5-(2-77 ethylhexyl-3-fluoro)thiophen-2-yl)-benzo[1,2-b:4,5-b’]dithiophene))-alt-(5,5-(1’,3’-di-2-78 thienyl-5’,7’-bis(2-ethylhexyl)benzo[1’,2’-c:4’,5’-c’]dithiophene-4,8-dione)] (PM6)2, 79 c) 2,2’-[(4,4,9,9-Tetrahexyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b’]-dithiophene-2,7-80
diyl)bis[methylidyne(3-oxo-1H-indene-2,1(3H)-diylidene)]]bis-propanedinitrile (IDIC)3, 81 d) Poly(4-butyltriphenylamine) (Poly-TPD), e) Phenyl-C61-butyric acid methyl ester 82 (PC61BM), f) Poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b']dithiophene-2,6-83 diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl)] 84
(PTB7-Th)4. 85
86
87
4
88
Figure S2. Intensity-dependent photoluminescence quantum efficiency on multiple Y6 89 thin films (normalised). Measurements were performed on separate days, on 4 different spots 90
on two different spin-coated films. Films were exposed to air for between 2-6 hours during the 91
measurements. Primary sources of error arise from slightly different film thicknesses of 92
different films and different excitation spots, and fluctuations of laser power. A rise in PLQE 93 with intensity is still clearly observed in the ensemble data. 94
95
96
97
98
99
5
100
Figure S3. TA spectra and kinetics of Y6 in solid solution of polystyrene versus neat film. 101
a) Time-slices of Y6 in a solid solution of polystyrene (1:50 weight ratio), at low excitation 102 fluence of ~0.5 µJcm-2. The spectra is markedly different to the thin-film spectra shown in main 103 text Figure 2a, where there is no longer-lasting red-shifted negative peak, indicating only 104 excitons are present. b) Kinetics of the excitonic peak of the Y6 in polystyrene, in blue, versus 105
the extracted charge/CT kinetics from a neat thin film of Y6 showing a much longer decay. 106
107
108
109
110
Figure S4. Fluence dependent exciton kinetics from transient absorption. A fast fluence 111 independent decay is present in the first picosecond of the exciton kinetics, extracted by genetic 112 algorithm from transient absorption measurements at specified excitation intensities, pumped 113
with 700 nm pulses. 114
115
116
6
117
Figure S5. Excitation energy-dependent exciton kinetics from transient absorption. 118
Pumped with intensities giving approximately 2.5 × 1014 carriers/cm3, the exciton kinetics are 119 the same for the different excitation wavelengths. 120
121
Figure S6. Evidence of long-lived triplets in Y6 neat thin film transient absorption. a) 122
Time-slices of un-normalised spectra at later times (beyond 100 ps) of neat Y6 excited at 123 5 × 1014 carriers/cm3, with 700 nm, 150 fs pulses. A rise in the broad negative signal, consistent 124
with the triplet signature identified by Gillet et al.5 around 1200 nm, can be seen after ~800 ps. 125 b) Exciton, charge and triplet kinetics extracted from use of a genetic algorithm to the spectra 126
in Fig S5a. The triplet kinetic is dominant after ~500 ps, though the signal is noisy. c) Exciton, 127 charge and triplet kinetics taken from the peak positions of the respective species (915 nm, 128 980 nm, and 1200 nm), normalised, showing the growth of the triplet species after 600 ps while 129 the charge species decays. 130
131
132
133
134
7
135
136
137
138
139
140
141
Figure S7. Optically-pumped time-resolved terahertz absorption kinetic of neat Y6, 142
compared to transient absorption kinetic decays of excitons and charges. The Terahertz 143 measurement is pumped by 800 nm, 150 fs pulses. The roughly matching Thz, and transient 144 absorption kinetics indicate that the two measurements are at roughly the same excitation 145
density, calculated as 5×1015 cm-3 for the Thz measurement, and 6×1015 cm-3 for the transient 146 absorption measurement. 147
148
149
150
151
152
153
154
8
Kinetic models of Singlet, CT-state, and Free Charge interconversion 155
156
Model 1: Explicit treatment of CT state population: 157
158
Equation S1 shows the coupled rate equations and rate constants employed to represent 159
this model. 160
. 161
𝑑𝑆
𝑑𝑡= −(𝑎𝑠,𝑁𝑅 + 𝑎𝑠,𝑅 + 𝑎𝑠,𝑠𝑝𝑙𝑖𝑡)𝑆 − 𝑏𝑠,𝑁𝑅𝑆2 − 𝑏𝑠,𝑐𝑡,𝑓𝑐(𝐶𝑇1 + 𝐶𝑇3 + 𝐹𝐶)𝑆 + 𝑎𝑐𝑡,𝑓𝑢𝑠𝑒𝐶𝑇1 162
𝑑𝐶𝑇1
𝑑𝑡= −(𝑎𝑐𝑡,𝑁𝑅 + 𝑎𝑐𝑡,𝑠𝑝𝑙𝑖𝑡 + 𝑎𝑐𝑡,𝑓𝑢𝑠𝑒 + 𝑎𝑐𝑡,𝑖𝑠𝑐)𝐶𝑇1 − 𝑏𝑐𝑡,𝑁𝑅𝐶𝑇1
2 − 𝑏𝑠,𝑐𝑡,𝑓𝑐𝑆 ∙ 𝐶𝑇1 + 𝑎𝑠,𝑠𝑝𝑙𝑖𝑡𝑆163
+ 𝑎𝑐𝑡,𝑓𝑢𝑠𝑒𝐶𝑇3 + 1
4𝑏𝑓𝑐,𝑓𝑢𝑠𝑒𝐹𝐶 164
𝑑𝐶𝑇3
𝑑𝑡= −(𝑎𝑐𝑡,𝑁𝑅 + 𝑎𝑐𝑡,𝑠𝑝𝑙𝑖𝑡 + 𝑎𝑐𝑡,𝑖𝑠𝑐)𝐶𝑇3 − 𝑏𝑐𝑡,𝑁𝑅𝐶𝑇3
2 − 𝑏𝑠,𝑐𝑡,𝑓𝑐𝑆 ∙ 𝐶𝑇3 + 𝑎𝑠,𝑠𝑝𝑙𝑖𝑡𝑆 +3
4𝑏𝑓𝑐,𝑓𝑢𝑠𝑒𝐹𝐶165
+ 𝑎𝑐𝑡,𝑓𝑢𝑠𝑒𝐶𝑇1 166
𝑑𝐹𝐶
𝑑𝑡= −𝑎𝑓𝑐,𝑁𝑅𝐹𝐶 − 𝑏𝑓𝑐,𝑓𝑢𝑠𝑒𝐹𝐶2 + 2𝑎𝑐𝑡,𝑠𝑝𝑙𝑖𝑡(𝐶𝑇1 + 𝐶𝑇3) 167
Where, S, CT1, CT3, and FC are the singlet, charge-transfer (singlet-like), charge-transfer 168
(triplet-like), and free charge (polaron) state concentrations, and the a and b rate constants are 169
given in Table S1. Key simplifying assumptions are that: the charge splitting rate from CT1 to 170
FC, and from CT3 to FC are the same, as are the S-CT, and S-FC bimolecular annihilation rates. 171
The bimolecular and monomolecular rates of CT1 and CT3 decay are also the same, (a higher 172
CT1 to CT3 intersystem crossing rate6 will make this assumption more accurate) 173
174
175
176
177
178
179
180
181
9
Table S1. Rate constants based on Singlet-CT state-free charge model from transient 182
absorption and PLQE measurements. 183
184
Species Prompt
fraction
Monomolecular rates (s-1) Bimolecular rates (cm3s-1)
Singlet 0.7** Geminate
non-radiative
𝑎𝑠,𝑁𝑅 ∗ 3.5 × 109 S-S
annihilation
𝑏𝑠,𝑁𝑅 2.0 × 10−8
Geminate
radiative
𝑎𝑠,𝑅 ∗ 0.4 × 109
S-CT, S-FC
annihilation
𝑏𝑠,𝑐𝑡,𝑓𝑐 2.6 × 10−8
Singlet→
CT1
𝑎𝑠,𝑠𝑝𝑙𝑖𝑡 0.6 × 109
Charge-
Transfer
0.1 CT1→
Singlet
𝑎𝑐𝑡,𝑓𝑢𝑠𝑒 2.0 × 109 CT-CT
annihilation
𝑏𝑐𝑡,𝑁𝑅 2.2 × 10−8
CT1→
Free Charge
𝑎𝑐𝑡,𝑠𝑝𝑙𝑖𝑡 1.7 × 109
Geminate
non-radiative
𝑎𝑐𝑡,𝑁𝑅 2.2 × 109
CT1 ↔ CT3 𝑎𝑐𝑡,𝑖𝑠𝑐† 1.0 × 109
Free
Charge
0.2 Geminate
non-radiative
𝑎𝑓𝑐,𝑁𝑅 1.2 × 109 Non-
geminate
radiative
𝑏𝑓𝑐,𝑓𝑢𝑠𝑒 2 × 10−6
*Rate constants estimated from TA and PLQE of Y6: polystyrene blends. 185
** Prompt singlet fraction is fixed by experiment. Free charge fraction here represents number of free charge 186 pairs, which is converted into absolute number of free charges as an initial condition of solving the differential 187 equations. 188
†Estimated from [Hou et al.6] 189
190
The fitted values here are illustrative of a fit that has low (relative) variance to the transient 191
absorption data, and also reproduces the rise and decay in PLQE, as seen in figures 3b and 3c 192
of the main text. With nine free parameters, the interdependency, and hence uncertainty of each 193
individual parameter is substantial, though each fitted value falls within a range that appears 194
physically plausible – for instance, the S-S annihilation rate, 𝑏𝑠,𝑁𝑅 =2.0 × 10−8 cm3s-1 is lower 195
than previous literature determinations of this value7, as would be expected from our new 196
interpretation, but is still only 10 times lower than previous measurements. 197
We can use the model above to put conservative bounds on the minimum steady-state free 198
charge fraction, at a given excitation density. For a wide range of the above recombination 199
10
constants, we calculate the theoretical PLQE. If the PLQE at an excitation density of 1016 cm-3 200
is greater than the PLQE at 1013 - 1015 cm-3, we calculate the error associated with the global fit 201
of the kinetic model to the fluence-dependent transient absorption kinetics of singlets and free 202
charges+CT states, and also the steady-state free charge fraction. If the calculated PLQE shows 203
no rise with increasing excitation density, it is not consistent with the rise shown in our 204
experimental PLQE data (of ~10% of max PLQE), and therefore is not included for error 205
analysis. Figure S7 shows the results of this analysis. There exist 3 local minima in the variance 206
to the TA kinetics, however we see that even with our conservative exclusion criteria (only 207
requiring a rise in PLQE with fluence of any magnitude), the model cannot admit solutions 208
where the steady state free charge fraction is lower than ~0.25 (or higher than 0.8). 209
210
211
212
Figure S8. Variance of Model 1 kinetics compared to measured TA kinetics for simulated 213
PLQE’s that include a rise in value with fluence. Kinetics were normalised before 214
calculating the error. 215
216
217
218
219
220
221
222
223
11
224
Model 2: Only Singlet and Free Charge, no explicit CT states: 225
Equation S2 shows the coupled rate equations and rate constants employed to represent 226
this model. 227
𝑑𝑆
𝑑𝑡= −(𝑎𝑠,𝑁𝑅 + 𝑎𝑠,𝑅 + 𝑎𝑠,𝑠𝑝𝑙𝑖𝑡)𝑆 − 𝑏𝑠,𝑁𝑅𝑆2 − 𝑏𝑠,𝑓𝑐𝐹𝐶 ∙ 𝑆 +
1
2𝑏𝑓𝑢𝑠𝑒 ∙ 𝐹𝐶 228
𝑑𝐹𝐶
𝑑𝑡= −𝑎𝑓𝑐,𝑁𝑅𝐹𝐶 − (𝑏𝑓𝑐,𝑁𝑅 + 𝑏𝑓𝑢𝑠𝑒)𝐹𝐶2 + 2𝑎𝑠,𝑠𝑝𝑙𝑖𝑡 ∙ 𝑆 229
Where, S, and FC are the singlet, and free charge (polaron) state concentrations, and the a and 230
b rate constants are given in Table S2. 231
Table S2. Rate constants based on singlet-free charge model from transient absorption 232
and PLQE measurements. 233
234
Species Prompt
fraction
Monomolecular rates (s-1) Bimolecular rates (cm3s-1)
Singlet 0.7** Geminate
non-radiative
𝑎𝑠,𝑁𝑅 ∗ 3.5 × 109 S-S
annihilation
𝑏𝑠,𝑁𝑅 2.6 × 10−8
Geminate
radiative
𝑎𝑠,𝑅 ∗ 0.4 × 109
S-FC
annihilation
𝑏𝑠,𝑓𝑐 3.2 × 10−8
Singlet→ FC 𝑎𝑠,𝑠𝑝𝑙𝑖𝑡 0.6 × 109
Free
Charge
0.3** Geminate
non-radiative
𝑎𝑓𝑐,𝑁𝑅 0.9 × 109 Non-
geminate
radiative
𝑏𝑓𝑐,𝑓𝑢𝑠𝑒 6 × 10−8
Non-
geminate,
non-
radiative
𝑏𝑓𝑐,𝑁𝑅 1 × 10−8
*Rate constants estimated from TA and PLQE of Y6: polystyrene blends. 235
** Prompt singlet and charge fraction is fixed by experiment. Free charge fraction here represents number of free 236 charge pairs, which is converted into absolute number of free charges as an initial condition of solving the 237 differential equations. 238
239
12
240
Figure S9. Model 2, with no CT states, fitted to experimental TA, PLQE, and compared 241 to the Saha equation. a) Model 2, above, fitted to fluence dependent exciton and charge 242
kinetics from transient absorption. b) the same model overlaid on fluence-dependent PLQE 243 data c) Comparison of the free charge fraction calculated from the kinetics model, red line, to 244
a model from the Saha equation, blue line, with an effective mass of 1.7 me and exciton binding 245 energy, EB = 175 meV. 246
247
248
249
13
250
Figure S10. Variance of Model 2 kinetics compared to measured TA kinetics for 251
simulated PLQE’s that include a rise in value with fluence. Kinetics were normalised before 252
calculating the error. The error is calculated as described above for Model 1, specifying the 253
criteria as needing a rise in PLQE. The variance for this model is smaller than that found for 254
the more complex Model 1, and the smallest free charge fraction at steady state is ~0.74. In this 255
model, the variance minima occurs for a steady-state free charge fraction of between 0.74 and 256
0.83. 257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
14
Photon Reabsorption in thin films 275
Photon reabsorption effects in photoluminescence quantum efficiency (PLQE) measurements 276
were quantified as per Richter et al.8 We estimated the escape probability with the same 277
method8, based on the optical ellipsometric constants measured by Kerremans et al.9, giving a 278
conservative estimate of escape cone loss of 𝜂𝑒𝑠𝑐 = 15%. The externally measured PLQE, 279
including effects of reabsorption and photon recycling, is given by, 280
𝜂𝑒𝑥𝑡 = 𝜂 ∙ 𝜂𝑒𝑠𝑐
1 − 𝜂 + 𝜂 ∙ 𝜂𝑒𝑠𝑐 281
Where 𝜂 is the internal PLQE. With no photon recycling, 𝜂𝑒𝑥𝑡 = 𝜂 ∙ 𝜂𝑒𝑠𝑐 282
283
284
Figure S11. Simulated PLQE of Y6 with and without the effect of photon recycling. The 285 simulated, fluence dependent PLQE based on model 2 above, illustrating the small, but non-286 zero enhacement in externally measured PLQE expected due to photon-recycling in thin films 287
of Y6. 288
289
290
291
292
293
294
295
296
297
298
299
15
0.0 0.2 0.4 0.6 0.8 1.0 1.2-6
-4
-2
0
2
4
6
Y6 single component
Cu
rre
nt
den
sit
y (
mA
cm
-2)
Voltage (V)
with PCP-Na
with PEDOT:PSS
300
Figure S12. Current density-voltage (J-V) curves for single component Y6 devices with 301
different hole extraction layers. With PEDOT:PSS, PCE of the best performing device pixel 302
was 0.09%. With PCP-Na,10 the best performing device achieved 0.63% PCE. 303
304
305
Figure S13. Intensity dependence of short-circuit current density in a low range – from 306 0.024 to 0.1 suns. The blue line shows a fit to the current vs intensity with an exponent of 307
0.985, indicating small bimolecular and space-charge recombination losses at these very low 308 fluences. 309
16
0.0 0.2 0.4 0.6 0.8 1.0-10
-5
0
5
10
PTB7-Th:Y6
Cu
rre
nt
den
sit
y (
mA
cm
-2)
Voltage (V)
1:50
1:100
310
Figure S14. J-V curves for Y6 devices with very low donor content of PTB7-Th. For the 311
device with a ratio of PTB7-Th:Y6 ratio of 1:100, power conversion efficiency was 1.23%, and 312
for the 1:50 blend, PCE was 2.26%. 313
314
315
316
317
Figure S15. Exciton, electron, and hole dynamics in a 1:1.2 PTB7-Th:Y6 blend measured 318 by transient absorption. a) un-normalised transient absorption measurements of a blend film 319 excited with 800 nm, 150 fs pulses, at 1x1014 carriers/cm3. Exciton, Y6 charge, and PTB7-Th 320 charge kinetics are attained by using the genetic algorithm described in the main text, with 321
mask spectra also described in main text Fig 2. As expected, the PTB7-Th hole lags the Y6 322 charge signature rise. And the Y6 charge rise shows a higher prompt rise than the PTB7-Th 323 charge prompt rise b) Normalised kinetics of those shown in Fig S15a. 324
17
325
Figure S16. Exciton and charge kinetics for neat Y6 compared to Y6 blended with 0.2 326
weight fraction PCBM. a) Un-normalised exciton kinetics from transient absorption of neat 327 Y6 and Y6:PCBM measured at the same excitation density, approx. 5x1014 cm-3, excited with 328
800 nm, 150 fs pulses. b) the corresponding charge kinetics. While the exciton decay is 329 accelerated for the Y6 PCBM blend between 1- 800 ps compared to the neat Y6, the charge 330 decay is slowed in the blend film compared to the neat film. This supports the hypothesis that 331
increased quadrupolar fields in the blend film can delay charge recombination, and shift the 332 dynamic exciton-charge equilibrium slightly towards charges. 333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
18
Pair 1
E (eV) |𝑉| (meV)
Ex1 Ex2 CT1 CT2 GS
Ex1 1.73 - 46 36 5 9
Ex2 2.01 46 - 86 32 5
CT1 1.69 36 86 - 35 76
CT2 2.03 5 32 35 - 36
351
352
353
354
355
356
Figure S17. Energy levels and electronic couplings for localized exciton and CT states. 357
Calculations were performed on π-stacked molecular pairs extracted from the Y6 crystal 358
structures (Figure 5), with alkyl chains truncated to ethyl to reduce computational expense. 359
Localized states were obtained from a separate calculation in which the molecules were 360
separated from one another by 10 Å. At this distance, interactions involving orbital overlap are 361
negligible, resulting in the formation of localized CT states. Localized excitonic states were 362
obtained by applying the fragment excitation difference diabatization scheme to the relevant 363
adiabatic states of the reference system.11 The non-orthogonality of the localized states in the 364
crystal geometry is accounted for by application of a Löwdin orthogonalization, however we 365
note that the effect of this procedure on the calculated values is minor in the present example.12 366
367
368
Figure S18. Ionization energy (IE) and electron affinity (EA) calculated using long-range 369 polarizable embedding of charges in a model thin film. Calculations were performed for all 370 molecules (1536 in total) in a 10 nm thick model thin film based on molecular dynamics 371
equilibration of the Y6 crystal structure. Dashed lines indicate the DOS onsets determined by 372 photoelectron spectroscopy in air (-IE), and inverse photoemission spectroscopy (EA).13 373
374
375
376
Pair 2
E (eV) |𝑉| (meV)
Ex1 Ex2 CT1 CT2 GS
Ex1 1.72 - 38 72 23 4
Ex2 2.02 38 - 55 85 8
CT1 1.69 72 55 - 65 59
CT2 1.86 23 85 65 - 30
Pair 3
E (eV) |𝑉| (meV)
Ex1 Ex2 CT1 CT2 GS
Ex1 2.00 - 37 25 35 19
Ex2 2.01 37 - 35 25 4
CT1 2.02 25 35 - 0 5
CT2 2.04 35 25 0 - 3
19
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