TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The at least one donor-acceptor heterojunction is formed at an interface of a material comprising (I) and the material is a donor or an acceptor, when the device is a solar cell. The organic photosensitive optoelectronic device further comprises: at least one electrode or charge transfer layer comprising transparent collecting electrodes; a buffer layer between the transparent conducting oxide and (I); and a layer of 60C immediately adjacent to (I). The substrate further comprises at least one electrode or charge transfer layer comprising transparent collecting electrodes. (I) is amorphous and is not symmetric. (I) has a thickness of 100 Angstrom or less. The at least at one point, the 60C has direct contact with the substrate. Preferred Method: (I) is deposited by one or more processes comprising vacuum deposition or solution processing. The solution processing comprises one or more techniques comprising spin coating, spray coating, dip coating or doctor's blading. (I) is sublimed during vacuum deposition one or more times. (I) is deposited at a rate of 0.1-1.5 Angstrom /second. The method further comprises: depositing 60C on (I) by vacuum deposition or vapor deposition; and depositing at least one layer of copper phthalocyanine or N,N'-di-1-naphthyl-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (NPD) on the substrate prior to depositing (I). The 60C is deposited at a rate of 2-6 Angstrom /second. Copper phthalocyanine and (I) are deposited together to form a layer comprising their mixture. Depositing (I) forms a discontinuous layer. The method comprises depositing 2 or more different squaraine films to form the donor-acceptor heterojunction.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The buffer layer comprises at least one of copper phthalocyanine and NPD. (I) is 2,4-di-3-guaiazulenyl-1,3-dihydroxycyclobutenediylium dihydroxide, 2,4-bis(4-(N,N-dipropylamino)-2,6-dihydroxyphenyl, 2,4-bis(4-(N,N-diisobutylamino)-2,6-dihydroxyphenyl or their salts. The donor-acceptor heterojunction is formed from at least two different (I). The donor-acceptor heterojunction is a mixed or bulk heterojunction. Preferred Definitions:    Ar1, Ar2 = substituted phenyl compound of formulae (II) or (III), or fused cyclic compounds of formula (IV);    X = H, alkyl, alkoxy, halo or OH (preferred);    Y1 = H or amino (optionally substituted), preferably NR1R2;    R1, R2 = alkyl (preferred) or aryl (both optionally substituted) or H;    Z = linking group;    n = 0-6; and    A ring, B1 ring = 4-8C rings (optionally substituted), which are fused to form 6-14C bicycle ring system (optionally saturated).    EXAMPLE - The thickness of spin cast 2,4-bis (4-(N,N-diisobutylamino)-2,6-dihydroxyphenyl) squaraine (SQ) film was controlled by the concentration of SQ solution, which was in a dichloromethane (DCM) solvent. By dissolving of SQ (3 mg) in DCM (2 ml), a SQ solution with 1.5 mg/ml concentration was obtained. The spin cast SQ thin film (80 Angstrom ) was prepared by spin coating SQ solution on a pre-cleaned indium tin oxide (ITO) with spin rate of 3000 rpm for 40 seconds in air. Next 60C, bathocuproine (BCP) and aluminum cathode were deposited on spin cast film under high vacuum to give the device structure comprising ITO/spin cast SQ (80 Angstrom )/60C (400 Angstrom )/BCP (100 Angstrom )/aluminum (1000 Angstrom ).