$B$	full width at half maximum
$d$	distance between crystallographic planes (d-spacing)
$L_D$	diffusion length
$M_n$	number average molecular weight
$M_{n,1\mathrm{or}2}$	number average molecular weight of component 1 or 2
$M_w$	weight average molecular weight
$M{W}_s$	molecular weight of a solvent
$P$	pressure
${\mathrm{P}}_{\mathrm{A}}$	polymer acceptor
${\mathrm{P}}_{\mathrm{D}}$	polymer donor
$R$	the gas constant
$r_{1\mathrm{or}2}$	relative molar volume of component 1 or 2
$T$	temperature
$T_c$	crystallization temperature
$T_g$	glass transition temperature
$T_m$	melting temperature
$t$	crystallite size
${\widehat{V}}_s$	molar volume of a solvent
$\Delta G_m$	Gibbs free energy of mixing
$\Delta H_m$	enthalpy of mixing
$\Delta S_m$	entropy of mixing
$\delta$	solubility parameter
${\delta }_{i\mathrm{or}j}$	solubility parameter of component i or j
$\theta$	diffraction angle
$\lambda$	X-ray wavelength (= 0.154 nm)
${\mu }_n$	electron mobility
${\varphi }_i$	volume fraction of component i
${\rho }_{1\mathrm{or}2\mathrm{or}s}$	density of component 1 or 2 or solvent
$\chi$	Flory–Huggins interaction parameter
${\chi }_{ij}$	Flory–Huggins interaction parameter between component i and j
${\left({\chi }_{12}\right)}_{crit}$	Flory–Huggins interaction parameter between component 1 and 2 at critical point
AFM	atomic force microscopy
all-PSCs	all-polymer solar cells
CB	chlorobenzene
CF	chloroform
DCO	1,8-dichlorooctane
DIO	1,8-diiodooctane
DMA	dynamic mechanical analysis
DSC	differential scanning calorimetery
FWHM	full width at half maximum
L–L	liquid–liquid
L–S	liquid–solid
NBR	butadiene/acrylonitrile copolymer
NG	nucleation and growth
ODT	1,8-octanedithiol
OPV	organic photovoltaics
OTFT	organic thin-film transistor
P(NDI2OD-T2)	poly{(N,N′-bis(2-octyldodecyl)naphthalene -1,4,5,8-bis(dicarboximide)-2,6-diyl)-alt-5,5′-(2,2′-bithiophene)}
PCE	power conversion efficiency
PCPDTBT	poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta [2,1-b;3,4-b′]dithiophene) -alt-4,7(2,1,3-benzothiadiazole)]
PDI	polydispersity index
PPO	polystyrene-poly(2,6-dimehtyl -1,4-phenylene oxide)
PVC	poly(vinyl chloride)
r-reg P3HT	regioregular poly(3-hexylthiophene-2,5-dyil)
SD	spinodal decomposition
TGA	thermogravimetric analysis
TGBC	top-gate bottom-contact
UCST	upper critical solution temperature
XRD	X-ray diffraction