Table 1.

Summary of properties of TE materials prepared via various bottom-up methods

Process type	TE Materials	Mechanism on property improvement	σ (S cm−1)	S (μV K−1)	κ (Wm−1 K−1)	PF (μW m−1 K−2)	ZTmax	Temp. (K)	Refs.
0D nanoparticles & nanoinclusion
Colloidal synthesis	PbSe quantum dot films	Quantum confinement, phonon scattering	~ 240	~ 425	~ 1.15	–	1.37	400	[83]
	PbTe/PbS nanocrystal films	Quantum confinement, phonon scattering	~ 21	~ 490	~ 0.675	~ 450	0.3	405	[84]
	PbTe@PbS core–shell nanoparticle pellets	Phonon scattering	125	− 185	0.53	–	1.03	710	[86]
Hydrothermal synthesis	SnTe nanocrystal pellets	Phonon scattering energy filtering	600	90	0.60	350	0.49	803	[91]
	Cu2S microcrystal pellets	Phonon scattering	100	120	0.2	–	0.38	573	[92]
Electrodeposition process	Bi2Te3 nanocrystals on PEDOT films	Phonon scattering	691	− 146	–	1473	–	298	[96]
	Gold nano-particles-BiTe composite pellets	Phonon scattering	71	− 380	0.5	–	0.62	298	[98]
Nanoinclusion	Pt nanoparticles in Bi2Te2.7Se0.3thin films	Energy filtering, phonon scattering	720	220	–	3510	–	298	[107]
	Ag nanoparticles in Bi2Te3 nanopowder pellets	Energy filtering, phonon scattering	525	− 140	0.58	–	0.77	475	[108]
	Ag nanocrystals in PbS nanocrystal pellets	Energy filtering, phonon scattering	660	− 200	0.8	> 1000	1.7	850	[109]
1D Nanowires/nanofibers/nanotubes
Solution-phase synthesis	Bi2Te3 NW pellets	Phonon scattering	430	− 240	1.0	2520	0.96	380	[116]
	PbTe NW pellets	Phonon scattering	95	295	0.9	850	0.33	350	[117]
	Bi2Te2.7Se0.3 NW pellets	Phonon scattering	465	− 160	0.46	1023	0.75	320	[122]
	Te–Bi2Te3 NW pellets	Energy filtering, phonon scattering	5.244	588	0.309	~ 300	0.236	400	[120]
	PbTe–Bi2Te3 NW pellets	Energy filtering, phonon scattering	100	− 310	0.51	~ 950	1.2	620	[124]
	Ag2Te–Bi2Te3 NW pellets	Energy filtering, phonon scattering	28	275	0.2	210	0.41	400	[123]
Template-assisted electrodeposition method	Bi0.5Sb1.5Te3 NW membranes	Phonon scattering	78	138	–	153	–	298	[143]
	Bi38Te55Se7 NW thin films	Phonon scattering	2200	− 115	–	2820	–	298	[149]
	Bi15Sb29Te56 NW thin films	Phonon scattering	720	156	–	1750	–	298	[149]
Electrospinning	PbTe nanotube mats	Quantum confinement, phonon scattering	0.148	196	–	0.567	–	298	[163]
2D Nanoflake/nanosheet /nanoplate
Chemical vapor deposition	Ag-doped SnSe nanoflake thin films	Phonon scattering	5	370	–	66	–	300	[177]
Molecular beam epitaxy	Sb2.31Te3 thin films	Phonon scattering	1810	118	–	2520	–	298	[224]
Hydrothermal method	Ge-doped SnSe nanoplate pellets	Phonon scattering	70	275	0.18	510	2.1	873	[192]
Solvothermal method	Bi2Te3 nanoplate films	Phonon scattering	122	− 103	–	128	–	298	[196]
	Bi2Te3 nanoplate pellets	Phonon scattering	600	− 137	0.1	1057	0.97	420	[197]
	Bi2Te3 nanosheet pellets	Phonon scattering	735	− 180	1.2	2400	0.69	333	[225]
	Bi2Te2.7Se0.3 nanoplate pellets	Phonon scattering	480	− 198	0.72	1875	1.23	480	[198]
Solution-phase synthesis	SnSe nanoplate pellets	Phonon scattering	31	320	0.55	375	1.05	805	[226]
	Sn0.94Bi0.06Se nanosheet pellets	Phonon scattering	12.5	− 285	0.3	100	0.21	719	[201]
	SnSe nanoplate pellet	Phonon scattering	35	340	–	400	–	550	[204]
3D porous nanostructure
Random porous structure	PbS nanocrystal monolith	Phonon scattering	~ 400	~ 187	0.56	1375	1.06	838	[207]
	Bi0.5Sb1.5Te3 powder monolith	Phonon scattering	403	173	0.27	1100	1.29	327	[208]
	Nanoporous SnSe pellets	Phonon scattering	~ 40	~ 325	0.24	506	1.7	823	[217]
Template-assisted uniform porous structure	Bi1.5Sb0.5Te3 film	Phonon scattering	644.5	144	0.89	1250	0.56	400	[209]
	ZnO film	Phonon scattering	~ 45	~ 253	~ 3.6	290	0.072	693	[210]
Nanoscale doping
Hydrothermal method	Pb, Cd-doped poly-crystalline SnSe	Phonon scattering, carrier concentration	~ 85	~ 285	0.23	750	1.9	873	[215]
Hydrothermal method	Pb, S-doped poly-crystalline SnSe	Phonon scattering, carrier concentration	~ 38	~ 325	0.13	418	1.85	873	[218]
Hydrothermal method	Se quantum dot/Sn 0.99Pb0.01Se nanocomposite	Phonon scattering, energy filtering	~ 31	~ 420	0.245	560	2.0	873	[214]
Solvothermal method	Cd-doped poly-crystalline SnSe	Phonon scattering, carrier concentration	79	295	0.33	690	1.7	823	[227]
Solvothermal method	Cu-doped poly-crystalline SnSe	Phonon scattering, carrier mobility	56	316	0.32	557	1.41	823	[218]